C60/ Medium Duty Trucks

[bucket]

I came across an old '78 GMC dump truck that's been sitting under a tree for about a decade. I'm not exactly sure what model it is (C60, C65, whatever) because the only badging on the fender is "GMC High Sierra". I've talked to the owner (we are bailing his property) about it and he's willing to sell.

I'm trying to figure out what powertrains were available in '78. I was expecting a tall deck 366 when I popped the hood, but was surprised to find a small block sitting there. I can't tell if it's original, it looks odd to me because it has ram's horn manifolds, a short water pump, a Rochester 2bbl, and an early 60's style air cleaner lid. Were these parts still being used in the 70's in the bigger trucks? I'd really like to know what I'm dealing with before I agree to anything.

The trans is a 5 speed and it has a 2 speed rear axle. It also has a dump flat bed that's about 18 foot long I'd guess. The truck is extremely solid and the rubber has a lot of tread left. It was a running/driving truck when it was parked in that spot years ago, the owner just didn't need to use it anymore. That's all I know, lol.

 

[towjoe]

most just run a 350 small block. 366 was pretty popular also. If it had a 427 it would be a real good find. I have a C60 wrecker out back that has a 350/ 4 speed in it that was factory

 

[bucket]

So the short water pump and 2bbl is probably stock for a '78? Seeing all the older style parts made me wonder if the truck might have had a little 283 swapped in.

 

[towjoe]

yea medium duty trucks have a lot of strange options to them. I pulled a new goodwrench out of a grain truck while back for one of the wreckers and had to strip it almost to long block to use it.

 

[J Knight]

It sounds stock to me, they had such low gears and a 2 speed rear they really didn't need a 4 barrel or even high CI displacement.

 

[Stewzer55]

Got any pics of it?

 

[bucket]

Crappy cell phone pics, but yes. It ain't pretty though, it needs a LOT of cleaning. Owner said he would take $1500 for it.

 

[bucket]

Most of the crap on the paint is moss.

 

[bucket]

Critters have been leaving chewed nutshells on the motor and interior for who knows how long.

 

[RetroC10Sport]

They used the rams horn on small blocks well in to the 90s on school buses and 2+ton trucks, I believe.

 

[Skweegle89]

I would be all over that for $1000. Do away with the truck and make a dump trailer out of it.


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[bucket]

Also I noticed the master cylinder that appears to have a single line, and no booster (vac or hydroboost) behind it. Surely it's not manual brakes?

I would be all over that for $1000. Do away with the truck and make a dump trailer out of it.


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Na, I like it because of the truck part too, lol.

 

[Boonie]

my 48 6400 has the straight 6 and a 1 barrel. goes down the road much faster than I want to drive it. big brother just finished up putting a 350 in his 55 6100. our family tree leans a bit towards the old stuff.

 

[J Knight]

I see it has a 73-76 driver door and a 77-80 passenger door panel. Does it have a tach cluster in it?

 

[bucket]

I see it has a 73-76 driver door and a 77-80 passenger door panel. Does it have a tach cluster in it?

The driver door was replaced at some point, it used to be yellow. No tach cluster, but it did have an air gauge. I think it was vacuum, don't remember off hand.