The Stovebolt Site Forums The Shop Area General Truck Talk Looking for info on a '58 GMC 1-ton

Driving home yesterday I passed a '58 GMC 1-ton truck with a flatbed sitting "for sale" along the side of the road. I stopped in and asked about it in the hopes it was a pontiac-equipped truck because I've been looking for a pontiac powered gmc for a while now. It did, in fact, still have its original pontiac engine and 4-spd auto. The truck is in great shape, restored in the late 80's or early 90's, and appears to have been driven little since then. No appreciable rust other than a bit of surface rust at the seams on the firewall. It's got a flatbed on it with short stake-sides and duallies on the rear. Supposedly runs/stops/everything works well.

My first question is what's a fair price for a truck like this? GMC's with the pontiac mills are harder to find, but I was hoping more for a 1/2 or 3/4 ton truck. I haven't seen any in my area come up for sale in some time and I have no idea what the market is like for these larger ones.

Secondly, what rear end would this truck have and what kind of top speed and fuel mileage might I expect? I intend to put it to good use hauling gas engines and motorcycles to shows and need to be able to put up with it for distances of up to 200 miles each way on highways, so I'd like it to be able to do 65mph comfortably. If the rear end ratio is too steep for that, is it possible to swap it out?

Hy John Leatherman, I have no idea what a fair price would be, it seems to vary depending on where you are, and of course the condition of the vehicle. I think the ratio for a 1 ton is in the 5 to 1 ratio possibly 5.14 to 1, I think that a constant 65 m.p.h. would be pushing the engine pretty hard. Other ratios are available the more common is 4.56 to 1, or the somewhat elusive 4.1 to 1. does the truck currently have 18" wheels on it, if it has anything other than 18" or tubeless 19.5" on it, then you could upgrade to those and lower your r.p.m. at any given speed, hope that helps.

I am with 3b. about 55 mph max and maybe 10 miles to the gallon, probably less.

It has been discussed here many times and the consensus is usually the same. These old trucks will go 65 mph but they were built and designed to be operated at slower speeds. Think about everything involved so your safe.

A flatbed truck with duals might not be a 1-ton. Assuming its not a bigger truck, during the blue chip years there was a 3/4-ton dually and you might want to be sure which this is.

The 1-ton would be a model 250, a 3/4-ton a model 150.

The standard 1-ton gears are probably the 5.14 Bobb identified. The 4.56 was standard in a 3/4-ton and both those and the harder to find 4.11 gears which were available in later years are an easy swap into your original rear end housing. Finding the pumpkin with the gears you want is much harder than performing the swap.

If it's really a 1-ton, it will have extended front hubs, via a bolt-on piece outboard of the brake drum. I believe the dually 3/4 ton had a different setup for front brakes.
Jerry

The 3/4-ton dually had different wheels than the 1-ton, or at least the one I looked at did, but I'm pretty sure it was dually hubs in the front. The cab serial number will tell what it is.

Anyone have a picture of the difference between 1-ton and 3/4-ton front hubs? The front rims were the same as the rears (atleast they looked the same) and appeared to be bolted directly to the front drums. Not sure what "extension" you all are referring to. I wasn't looking carefully at the rims, but they didn't appear to be 18", they seemed smaller than that.

Where's the cab number and what differentiates the models in it? I'll try and get back up there next weekend, or contact the seller and get the number.

Also, not sure if it changes anything, but I did find the brakes a bit odd. The truck has power steering and the power brake system was hydroboost, not vacuum assisted. Looked factory. Was this an option on the 1-ton and 3/4, or perhaps specific to one size?

I can't answer the hyrdroboost question, I just don't know.

The serial number plate should be in the driver's side door opening on the cowl. The model portion of that number will either be 15 something or 25 something. 15 will be 3/4-ton while 25 will be 1-ton.

The 3/4-ton dually I saw had 150 in the grill and I commented it had the wrong model number for a 1-ton and a guy behind me proceeded to correct me. Turned out he was right.

Price is hard to talk about without looking at the truck in person. You can look it up in Old Car Price Guide to get a ball park. Those numbers always seem high to me. The real question is are you willing to pay what they want or can you read agreement on price.

Right now prices are a little depressed from where they were a few years ago. There are a lot of guys out there who spent big bucks on restoring trucks in the last ten years who would like to recover their investment and are unlikely to manage that.

A truck that was restored 20 years ago is likely priced more realistically in today's market.

Neither power steering nor hydroboost would have been original equipment, or even optional in 58. It looks like you've got one that's been upgraded to newer running gear sometime in the past. Does it still have a straight front axle?
Jerry

Edit: The brake pedal on all the trucks in 58 went through the floor, with the master cylinder mounted on the frame rail under the driver's floorboard. The only power brake option would have been a "Hydro-vac" unit, mounted remote from the master cylinder, usually behind the cab on a frame rail or crossmember.
Jerry

The power steering was an option on the "Blue Chip" Jimmies. The PS setup would include a saginaw style box that bolts through the frame, a Buick/olds/pontiac PS pump with a huge pulley, and a speacial steering colum with a rag joint connection. This setup is extremely rare and highly sought after, espeacially from the NAPCO guys.

Power steering was optional, starting in '55 for sure (I have one source that shows it for '54), but that system is the slave cylinder style with the hydraulic ram mounted to the axle, control valve in the drag link, and the pump is part of the generator (Chevrolet setup, unsure about GMC). Not very common.
Also, as Jerry mentions, the power brakes would have been the Hydro-Vac, not the Hydro Boost. Hydro-Vac was optional on trucks below 1.5 ton, standard on larger trucks.

I only got a quick look under the hood, so I could have been mis-interpreting some of the options. The brake pedal did still go through the floor, and it was still the stock front axle and stock brakes (or atleast it still looked stock, I don't know exactly what '58 GMC equipment looked like). There was a unit mounted onto the driver's side frame rail at about the same height as the exhaust manifold that looked like a reversed master cylinder. It was not attached to the firewall though, just the frame. Had a larger round cylinder on the front with steel lines running to and from, and a small master-cylinder that hung off the back pointing towards the firewall. As I said, it was a quick look over under the hood. It may have just been a standard remote reservoir? Anyone got a picture of a stock GMC brake master cylinder?

"but that system is the slave cylinder style with the hydraulic ram mounted to the axle, control valve in the drag link, and the pump is part of the generator (Chevrolet setup, unsure about GMC)."

As stated above GMC trucks from the 1955-1959 vintage used a power steering gear, not a ram assist setup like the chevy trucks of the vintage. Very rare, very desireable!

Intersting setup. Wonder why they didn't use the same one on Chevy? Certainly would have made things easier, both on factory supply parts, but also for retrofitting. Here's the manual page.