1975 GMC 6500 dump truck with 366ci gas big block

[Will_C]

I grew up in a family that had a small excavating business. My father had 1970 and 1979 Chevies with the 366 in both. Both trucks were bought new. As I remember, they were both relatively trouble free-I can't remember any engine problems with either one. They both had around 175,000 miles on them when they were replaced.

Dad had 6 yard boxes on both, and routinely hauled 9-10 tons of gravel. He also towed trailers that grossed 12-15 tons moving eqiupment around. The trucks were not fast fully loaded, but they worked well enough for him to make a comfortable living with.

The wheels are usually the split rims, viewed today as dangerous. Hydraulic brakes and a two speed axle and a 5 speed transmission were the usual drivetrain options. If I recall correctly, those trucks got about 5-6 mpg-no matter if they were loaded or empty.

I do remember the 1970 cost $6800 new!!

Will

 

[RickB]

If I recall correctly, those trucks got about 5-6 mpg-no matter if they were loaded or empty.

Will

I once owned an IH Fleetstar with a 549 gas engine. It wouldn't have gotten better than 5 MPG on the way down if I had driven it off a cliff.

 

[Dargo]

I'm assuming it's hydraulic brakes since you said booster and cylinders. IMO air brakes are easier to work, cheaper to repair, and stop better. Not sure how GM does it but my international has a master that feeds a second master with a booster mounted under the drivers door. From what I read the two things to look out for is the diaphram in the booster leaking and the seals in the cylinders leaking. Probably why they were replaced.

I would be ready to rebuild that carb as it may not like Ethanol gas. Some other things to look at would be the leaf springs, they can get rusty and swell. It's not that you can't change them yourself but they are heavy. Also look at the grease fittings, do they look like they were used? Also take a look at the steering linkage, sometimes they are costly. For around the house some slop isn't a problem but driving on the road with a load you'll want to fix it.

My international's hydraulic pump leaked where the shafts come out of it. It's a pretty easy and cheap fix but you need to go to a hydraulic shop to get the correct seals. Over all because of it's age rubber parts are probably going to br dried out and can fail.

I would expect between 2 to 6 mpg driving it on the road. but if you need some gravel around the house having your wn truck is invaluable. I could never live without mine as I'm always landscaping or filling spots. If it's in good shape I would buy it.

This silly old dump truck is really on my nerves now. I'd pretty well written it off as "too old". However, being a 1 owner and the owner being a guy who gives a new meaning to "****" on taking care of stuff, I'm really thinking about the old dump.

I didn't think to take any pictures, but other than collector cars, I've never seen a 1975 vehicle in such good condition. Anyway, I made no commitment nor offer of any sort, but I'm going to look at it again on Monday and drive it a bit more. Heck, it's almost too nice for what I want! The glove box has a log book listing every oil change, every fuel fill, every greasing etc. since it was new. The dang floor in it isn't even dirty and I dropped by to see it today unannounced, so it wasn't cleaned for me. He just mentioned to my father this morning that he ought to sell the old thing since it just sits except for his scheduled run times to keep all the seals from drying out. I dunno. I know I can get it for $2500. I'm clearly hoping for less. I guess I'll see. My wife may say that since both barns are completely full, I can't have it. Ooh, that would hurt!

 

[JESSE1]

Get the truck. Parts shouldn't be too hard to get for it. A '75 is new compared to the trucks I have. The cab is the same as used in the GM pickups so if you need weatherstripping or windshield gaskets or any other cab parts they should be easy to get.

A '75 qualifies as an antique so you should join the American Truck Historical Society American Truck Historical Society if you buy it. Lots of good info on our discussion forum. There should be an ATHS chapter close to you.

 

[Ryan03]

If it is as clean as you say, in good working order, and the juice brakes were recently freshened, I say go for it. Even if it is nearly 36 years old. It is probably worth around a grand just in its scrap weight, so a good chunk of the purchase price could be recovered no matter what.

As far as the wife veto, just tell her it followed you home.

 

[flusher]

Anybody on here ever have one of these? I don't really need a dump truck right now, but this is a one owner a family friend owns and has never sat outside overnight and I can't find any rust anywhere on the truck. He had the bed removed, media blasted and painted with some hard enamel paint about every 5 years. It has average tires, new brake booster and wheel cylinders, original interior that doesn't even have a rip in the seat and has 29,XXX miles on it.

I really don't know anything about the old 366 truck engines (he says it's a big block), but it started right away after sitting for weeks, didn't smoke and idled just fine. I wouldn't even consider this thing except it's darn near in perfect condition and I think I can get it for a reasonable price.

My questions are; is that a decent truck? It's bed looks good and is a 6 yard bed and the engine, transmission and brakes are good. My next question is what really would be a "reasonable" price for something that old?? I can't really go out of a book, because it looks better than some 2009 trucks I've seen. Any thoughts or comments on that old truck? My use would really be moving dirt on my property and saving time and wear on my tractor moving dirt 1 yard at a time.

Here's what Wikipedia says about that engine:

366
The 366 Big block V-8 (6.0 L) gasoline engine was used only in Chevrolet Medium duty trucks and in school buses. It had a bore of 3.935" and a stroke of 3.760". This engine was made from the 1960s until the mid-1990s. The 366 used 3 compression rings on the pistons as it was designed from the very beginning a truck engine. The 366 is a tall deck motor.

Chevrolet Big-Block engine - Wikipedia, the free encyclopedia

With only 29K miles on it, it's hardly broken in yet .

I just bought a 2004 Isuzu NPR EFI that has the 6.0L (366 cid) V-8 Chevy gas engine in it. The truck is a 14ft stakebed, GVWR=12Klb, 49600 miles. The engine (LQ4) is considered a small block engine nowadays. With the 4-speed 4L80-E automatic tranny and a 4.78 rear end, it moves right along on the freeway. It'll be the transporter for my smaller parade tractors (Farmall Super A, Minneapolis Moline BF).

 

[tcartwri]

I just bought a 2004 Isuzu NPR EFI that has the 6.0L (366 cid) V-8 Chevy gas engine in it.

Not sure if you're implying that this is the same motor, but it is not in any way related.

 

[GGB]

If you decide not to get it, I'd probably take it! We've been looking for a good one like that to use at our farm, and the one you are looking at sounds like a nice truck. We've wanting a small dump truck for hauling gravel and dirt.

We've got a 1975 Chevy Bruin with a 427 (tall truck block like the 366 you are looking at), twin screw, 5 x 4 tranny, and well over 200,000 miles, that we use to haul grain to the elevator. Basically it's a big brother to the one you described. It's a real beast, a lot of rust, but does the job. Just had a couple of leaf springs replaced and an air brake pot replaced, along with a couple of rear axle seals and a tuneup earlier this year. That was the first major work we've had to do to it in the 8 years we've had it.

Oh yeah, it gets great mileage! I doubt we get better than 5-6 unloaded, don't even want to talk about it when we're fully loaded. Let's just say we remind ourselves that we aren't using it every day! And for the price we paid for it, we can buy a lot of fuel.

What you have described is well worth the money-buy it and take as good care of it as it sounds like the current owner has, and you will probably sell it down the road and get your money back. Good luck!

GGB

 

[flusher]

Not sure if you're implying that this is the same motor, but it is not in any way related.

Correct. The 6.0L in my Isuzu is part of a different Chevy engine series.

 

[crazyal]

One thing about these trucks is they were built tough. Not a pickup truck. If you have land I don't know how you could be without a dump truck. They don't have much in the way of emissions to worry about.