This is probably more along the resto line of things, but I was in an old junkyard today and we came across a '56 GMC pick-up with the engine and complete Hydromatic set-up: trans, steering column, trans crossmember and under-floor pedal. This is the second one I've found in a junkyard in less than a year, but the other was crushed before I could learn anything about them. Is it worth going back and picking the carcass clean for the Hydro pieces, or should I just not worry about it? -Brad
I don't know-would be interesting, but maybe not valuable. I would love one in a Task Force truck, as my 55 Olds had one. Have only seen one other, myself. What engine is in the truck? Had a friend who ran a 57 sedan delivery in a stock class back in the day using a Hydro hooked up to a dual-quad 283. wish I was more (any) help.
Brad.. Having owned several 56 Pontiacs with the slant-pan hydro, I was told the 56 trannys had an extra set of clutches more than the 55 and earlier to help handle the power of the later engines.. I put a hotrod 389 in front of the last slant-pan hydro in a 56 Pontiac and it worked great....for awhile. It began slipping into 3rd gear and before I had a chance to address the problem, we bought a house and I had to sell it for finances to buy the house. If you decide to grab the tranny, be sure to also grab the throttle linkages and kick-down linkages associated with it.. Chevy also used that transmission in some of their mid 50s pickups with both V/8 and 6 cylinder engines...got a buddy with the parts to put one behind a SBC.
V8 engine? If so it's a Pontiac with a lot of one year only stuff. The exhaust crossover at the front is a real bitch to come by, grab that if nothing else.
GMC would be a 6 cylinder? I know that small block Hydro stuff is hard to come by and some of us like hydromatics. The 6 would be a 302??? maybe worth having for someone building a C or D gas car or even an altered.
The restorers love those trannies - if nothing else post it up at OldGMCtrucks.com so a member there can grab it.... And thst website has a great knowledge base in their small group of mostly stone-stock truck owners.
I have a 55 chevy truck with a 235 haydramatic that I drive daily and have owned for 15 years or so.I think the gmc hydramatic trucks are more common than the chevy ones,or at least I see them more often.I would say if you like original trucks and wanted something different go for it.If I was buying the engine and trans I would offer around 300 with the column and linkages as well as the transmission cover plate that bolts to the floor,it is different on standard trucks
General Motors/Chevrolet put 'Hydros' behind Chev V-8's - anybody know what years and what chassis? I think it was 56-57 Chev pickups with a V-8 and automatic (no PowerGlides in trucks). As mentioned above, GMC pickups had Pontiacs W/Hydros Some Chevy medium duty trucks 55-57 (maybe later) had Nailhead Buick engines but I think they were all standard trans, no automatics
This one is the Pontiac V8 set-up. Incidentally, anybody have an idea what the gear ratio in the rear end would be? I'm wondering if it'd be a more friendly ratio than the stick-shift equipped trucks. -Brad
on hamb, it was said that B&M used a lot of the Pontiac versions for the short tail shaft version. I don't recall if that thread said if the Pontiac did/didn't have better clutches. But that thread referred to car Pontiacs around 55 or so, not truck.
here on hamb the figure 3.08 on hydro was mentioned i can go out i shop and turn wheels on my 1958 gmc v8 hydro.and let you know it is a inrest for me allso.
Personally I would grab everything including the column and all linkages / kick down etc that hooks it up. I'm retaining the Hydramatic column in '46 Olds and hooking up a 700R. These parts are rare and getting harder to source these days.
If the GMC pickup is a stock 6 cylinder, it should be a 270, not a 302. The bigger trucks got the 302, but it's worth checking on. There is a 'pad' next to the distributor where the eng # is stamped. The beginning digits are the engine displacement. From what I seem to recall, automatic equipped Chevy pickups got Hydramatics from '54 through '59, both 6 and V8 models. Ray
I bought a Hydramatic trans that came out of a 56' Chevy pickup. It's a flatpan which I've been told came in the trucks rather than the slantpan and is supposed to be more desirable for performance build up. Also, they come with the smaller 10" torus which will give you a little higher stall.
save the whole truck - hard to find - had a '56 with the Pontiac V8 and hydro trans. wish I never sold it
I had heard that there was something unique to the starters in those hydro trucks, or maybe starter location in the bellhousing? Does anyone know?
wasn't just the hydro starters...same with my 57 bellhousing for a manual tranny on an early pontiac in a 57 GMC
The 56 slant pan hydros used in Pontiac and Olds did have more clutch plates and were a beefier transmission. Whether the truck versions were beefed is unclear.
My best friends race car tow truck was a '57 GMC CarryAll with a stock V8 Pontiac engine. I saw several mid 60's GMC's come in our shop in the late 60's with the stock Pontiac V8 and Hydramatic. It was a great combo!
Grab it all...there will be someone wanting to convert their manual to a hydramatic. I just did and to get it all in one pack of as a donor, someone would pay a good bit for it. Lee
Back about 1970 i had a 56 G M C short box, big glass in back, lots of chrome. It had the pontiac V/8 , 316 or some thing close to that , and 4 sd hydramatic. arm strong steering, but it was fun to drive. I believe the trany had a big scoop under it to cool it . They did put it behind the inline 6 and 55 /57 chevy v/8 engine . I sold it to some high school kid and he had it strung out with trany screwed up with in a year. It sat behind a transmission shop for about 2 years because the kid never had any money. The last i new about it was it got pretty well stripped just sitting there with no fence around it, to bad i would like to have it now.
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