This seems like a very good price for a classic GMC motorhome, the one that nearly every enthusiast at some level can agree is one of the coolest RVs ever built. These front-wheel-drive motorhomes have become cult classics of sorts, and you often see restored or survivor-grade examples pulling deep into the five-digit range. This 1978 GMC Royale is listed for what seems like a relative bargain here on craigslist with the seller claiming it’s been listed as part of an estate clean-out and priced at just $6,500. It does need some mechanical help but still turns over at the moment. Thanks to Barn Finds reader T.J. for the find.
The GMC Royale offered all the comforts of home in a slightly more convenient package, allowing novice motorhome owners to potentially slip into the driver’s seat with slightly smaller proportions to get used to. GM truly wanted to build one of the best-constructed motorhomes on the market when they introduced this model, so build quality is generally quite robust. While this can sometimes seem like a case of over-zealous marketing speak, the number of these Oldsmobile-powered RVs still in active use seems to validate those claims. This one looks fairly tidy inside despite apparently not seeing much regular use recently.
The seller has attempted to get the motorhome running, noting that they installed new batteries and can get the GMC to fire off but it doesn’t stay running. The mechanic they hired to assess the non-running issues pointed to the fuel pump as the likely culprit, which is historically the easiest answer when it comes to diagnosing a no-start or failure-to-run scenario. The good news is that getting a rig like this running is generally the easy part; de-funking a gross camper cockpit is usually the bigger challenge. Fortunately, in this case, the living and cooking spaces look quite nice along with the wood paneling and window coverings.
The seller mentions that as part of the estate sale, they are also listing a second motorhome along with a Jeep Wrangler and Mini Cooper S convertible. Both of those would make excellent tow-behind vehicles for an RV, so it does make you wonder if the previous owner had a seasonal setup or a long- versus short-haul configuration for his open-road adventures. Either way, assuming that the engine coms back to life with relative ease, this seems like an excellent price for a classic GMC motorhome.
This looks to be a real bargain to me. This has got to be one of the best thought out RV’s ever built. How many RV’s out there have the benefit of R&D from one of the largest truck manufacturers. Robust powertrain in the front allowed the vehicle to ride on a lower center of gravity while still retaining a comfortable standing height and the smooth riding bogey air ride tandem axles. I watched old video clips of these being punished on the proving grounds. If that wouldn’t sell you on the product I don’t know what will. I’m not sure what could be done but it would be nice if you could make a 4T90 transaxle out of the THM425 with the added benefit of overdrive and locking TQ. Add EFI to the 400ci Olds engine and squeeze a few more MPG’s out of it. Redo the interior to current trends and you would have yourself a RV that would still hold its own.
“Redo the interior to current trends…” This one’s a very good choice if that’s your gameplan since it’s already been done at least once so you won’t be ripping out original, and desirable, 1970s green paisley.
The interior doesn’t look that distinctive or cool vintage, so go for a modern re-do. Don’t go too cutting edge or that will become dated real quick.
Sadly, alphasud, I can’t imagine a practical way to add overdrive to one of these motorhomes. It’s front wheel drive, but doesn’t have a transaxle.
The THM425 is just a specialized Turbo 400 with a chain driven unit to redirect the power output to the front attached, but the front differential sits so close that it’s improbable that there’s sufficient room to add an aftermarket OD unit.
With some fabrication it might be possible to adapt a THM325-4L from a mid-80s Eldorado/Riviera/Toronado into it, but the Turbo 325s were developed for the smaller and lighter 1979-85 E-bodies equipped with lower output engines and weren’t as robust as the 425s. They were fine in their intended application, but it would be questionable as to whether or not it would be up to living behind that 403 and handling the weight of that motorhome.
Truth be told, it was probably the demise of the THM425 at the end of the 1978 model year that was the death knell for the GMC motorhome platform. The motorhome would have been its only remaining application, and the limited sales volume couldn’t possibly have justified the continued production of that transmission.
“R&D from one of the largest truck manufacturers’. Like often is the case in vehicle development, the Marketing and Styling departments can take precedence over engineering, resulting in functional compromise. These A class RVs can be compared to current B class favorably, but lack the function of “industry” A class. The GM Motorhome was engineered by the car division for 4500-5000 lb cars. The Motorhome is 10,500 to 12,500, with 30 gal fresh and 30 gallons waste water. My 26ft Winnebago is 16,000 empty and 21,000 gross. That includes 60 gal fresh, 40 gal gray and 40 gal black waste. The Winnie is on a Chevy Workhorse chassis with 494 BBC with 340hp. Real truck stuff The Workhorse chassis will support up to 38 ft RV and 26,000 lb. The GM is more like a Corvette.
It’s easy to make a stupid, unfavorable comparison when you select vehicles from two different eras. Keep in mind that Winnebago was still cutting its teeth building primarily Class C motorhomes on one ton van chassis in an era when they started with a whole van and cut off and threw away two thirds of it back in the early ’70s when the GMC motor home was developed.
At the time, the GMC actually compared quite favorably to what was then the market leading “big”, high end Class A of its era, the Travco motor homes built on a 440-powered one ton Dodge chassis. The 455 Oldsmobile/THM 425 drivetrain performed very well in motor home service, as it was over-engineered for the first generation E-bodies for which it was intended, and the rest of the motor home was quite advanced for its day, as compared to contemporary RVs.
It was the downsizing of GM’s automotive lines that brought about the demise of the GMC, not because it wasn’t competitive in its market segment. The discontinuation of the 455 in conjunction with the 1977 model year downsizing of the full-size lines hurt it, but it survived for two more years with the Olds 403. The loss of the THM425 for 1979, though, was its downfall.
Phil D: “It’s easy to make a stupid, unfavorable comparison when you select vehicles from two different eras”. This is a GM Motorhome not a GMC. The Winnebago Sightseer followed four years later. Alphasud touted truck R&D for the GM when it is made up of car parts and technology. Typical of GM to trade on form, not function or durability. The Winnebago uses, as I stated, Chevrolet truck technology.
If the GM was more like a Corvette then sign me up! To me your discussion has merit but what I was trying to emphasize was the GMC motor home in its time received more R&D and had the backing of one of the worlds largest manufacturers with some of the most talented engineers of the 60’s and 70’s when the UPP was developed. Construction practices were also cutting edge for its time. Yes the new Winnebago uses a workhorse chassis but bigger isn’t always better. I will bet in 30 years the Winnebago will fade away but the GMC will still be relevant. Reason why so many remain and are loved by those who own them. My friend still has his with the original interior. He owned another RV that was cutting edge for its time but never gained the status of the GMC. That would be a Vixen with BMW turbo diesel power.
403 olds I think.
Yes, it’s a 403 in this one. My mistake on the 400.
There are some good videos from a Florida shop that specializes in these units. They say the fuel lines cannot handle the ethanol fuel and must be replaced.
Also being unibody not good for towing a vehicle behind. Brakes are marginal too owned one with built engine and EFI which destroyed transmission and needed an upgrade too.
Wow I was sure when I clicked on the ad it would be gone. Great price for a vehicle that was sort of a halo for GM…they really went all in with these. Of course it’s hard to know just from the description but it sure sounds like the first place I’d go is replacing the fuel pump.
Like everyone I love these and have been fortunate, to have traveled in them. I would think this one would be a no brainer ,if you were planning on fixing it up and had the budget for doing it.
The VIN posted in the ad isn’t a 1978 GMC VIN. The posted VIN is 17 characters, which didn’t start until the 1981 model year. A 1978 GMC VIN is 13 characters and starts with the letter “T” for GMC division. Perhaps this is just a copy/paste mistake, but it needs to be explained.
Or a Craigslist scam. Of many
These are great classic RVs. The Olds 455/425 TH is simple but solid engineering. I’ve seen many put six figures or more into new air ride, gut & refurbish with modern luxury appliances/WiFi/Genset etc. tRhey are the AirStream of GM RVs.
The ad says it is a Royale which is a 26′ GMC. The interior photo is of a Birch Haven which is a 23′ GMC. This is quite obvious if you are familiar with these. The 23′ side door is farther forward than on the 26′.
Something is amiss here.
They did say they are preparing another of these for an auction it could be they mixed the photos accidentally
Not knowing anything about these I DO know that the large flat fuel tank has a tendency to rust out on the top. The frame where the rear suspension attaches is a rust-prone “weak” spot. I further understand that the end came for these due to some other line at GMC basically needing the space to build that product. Keeping a “consumer” vehicle in production or providing for their “bread and butter” commercial clients makes that a no-brainer. I am not a fan of front wheel drive but I’d overlook that if the right one of these showed up in my driveway. It looks more modern than the modern ones do!
We DO have to consider the price of FUEL to move something this big. Currently my Sprinter with a 2.7diesel is $.23/mile. Big V8 (carb) pulling this around? my eyes are watering….We’re talking aircraft style gallon per hour rates..
gone.
Condition being equal the 23 foot is worth more than the 26(?).
Unless the fuel pump is very very hard to get at here, not replacing it even yourself (the simple-as-pie mechanical pump for a 403 ’78 firebird costs as little as $16 from rockauto) – before trying to sell this motorhome, IMO, would be ridiculous.
Probably, as mentioned, the fuel lines are deteriorated so badly fuel can’t get to the engine, so they will need replacing along with the pump.