The Stovebolt Site Forums The Shop Area General Truck Talk 3/4 ton

Can anyone tell me the difference between 3/4 & 1/2 ton trucks? (other than the obvious rearend, 8 bolt wheels, etc) Is the body the Same?

Floating rear axles.

The body is the same.

What year?

Sorry Forgot the year 1948

All cab and front end sheet metal is the same. Bed will be longer on the 3/4 ton. Best bet is to pick up a copy of the Factory Assembly Manual and get yourself a Restoration Pack.

on the 3/4 ton (long bed) the spare fits w/o a "dent" in the rear fender

Except that side-mount spares weren't available from the factory until '53...

3/4-ton trucks also came standard with 4-speed SM420 transmissions. The drivelines are open rather than the torque-tube setup which was used through '54 on the 1/2-ton models. The brakes are larger all around.

The cab is identical. The frame is heavier gauge on the 3/4. Wheelbase for 1/2 116", 3/4 125". Bed length 1/2 6.5', 3/4 7.5'. Tires 1/2 has 4 ply, 3/4 6 ply. Gearing 1/2 4.11, 3/4 4.57. Springs 1/2 8 leaf, 3/4 2 stage 7 or 8 leaf.

Brakes. I don't have specifics on the 48, but the 1/2 had smaller brakes than the 3/4.

Tranny. 1/2 had either 3 speed column or 4 speed floor with one-piece enclosed driveshaft. 3/4 had only 4 speed floor with two-piece driveshaft, front half enclosed, rear half open.

Differential - 1/2 had a semi-floating differential, where the axles are loaded with weight of the truck. 3/4 had full-floating, axles carry no weight, only driveline (power) load.

1/2 ton 6 lug wheels, 3/4 8 lugs.

If you are trying to decide on which to get, I would recommend the 1/2 ton, mainly from the standpoint of availability of wheels, tires and suspension upgrades. Front suspension packages are available for the 1/2, not for the 3/4. Rear end swaps are easier to make, with many possiblities. Wheels and tires are also easy to obtain.

hey!! smarten up!! 3/4T's never had the short bed, but 1/2T's came in short or long bed

Bill

In the AD series they didn't. There was no such thing as a "short" or "long" bed available for the 1/2 tons. All of the AD 1/2 tons had the same bed length.

really!! :confused: they stopped makin long 1/2's for 7 years and then started again? wow

Bill

Only GMC's had the 1/2t long bed with thier more powerful and fully presurized inline 6's.
I think the 1/2 t beds are too short and the 3/4 ton bed is proportioned better. My .02

ahh, yes, I see lookin in the gallery a bit the long beds are all ND rather than AD, but I can't imagine it had anything to do w/ power, as the same engine powered all the trucks, right up to the biggest rigs, just a marketing/profitability thing I'd never noticed before - maybe cuz I'm not too keen on either AD's or stepsides long or short

Bill

Red58, as dave s stated, GMCs had different powerplants than Chevys. I don't think it was a marketing ploy. The fact is GMC used pressurized oiling while Chevy used splash oiling. Perhaps you should do more research to properly answer questions or dispute other's answers.

Phil

GMCs used a better alloy in the engine blocks, too.

I keep hearing about these partially-enclosed 3/4 ton driveshafts. When did these stop? I can't remember seeing that setup on my three 3/4 and 1-ton trucks from '52-'55.1. I'll take a better look this weekend.

GMCpanel wrote: "I keep hearing about these partially-enclosed 3/4 ton driveshafts. When did these stop?"

My '50, 3/4 ton has a closed driveline to a carrier bearing and then open from there to the differential. I have no idea when they stopped.

Kels

Several people have said that the 3/4-tons only had 4-speed trannys, but the standard transmission for the AD 3/4-tons was the 3-on-the-tree, with the 4-speed as an option. The 1-tons had the 4-speed as standard.

The enclosed front driveshaft on the AD 3/4-tons ended with the '54 models. All of the AD 1-ton drivelines were fully open.

Curt, you beat me to it.

Some of the confusion may be due to differences between the Chevy and GMC trucks. I cannot comment on the GMC, but Curt is dead on. The Chevy AD 3/4 tons had a three speed on the column as standard with the four speed a RPO (Regular Production Option).

On the driveline, if you don't believe us that the front was enclosed on the AD Chevy 3/4 tons, go read the Shop Manual, specifically page 4-52.

I have a 48, 3/4 ton daily driver and a 51, 3/4 ton complete rolling chassis if anybody needs pictures of any of the components. The rolling chassis is nice if I need to see how something is put together without crawling under the 48. The 48 and 51 are similar except that the 48 has lever shocks compared to the tube shocks on the 51, and bendix brakes on the 51 as opposed to the Huck on the 48.
Ralph

OK, I think I get it now...my only 3/4-ton is a 55.1 Chevy. The 1-tons are 52 and 54 GMC panels. I simply never noticed the stuff in the shop manual about the partially-enclosed divelines. My bad.

Can anyone point me to some good pictures of a '51 3/4 ton? I need to see the the hood emblems that were stock.

thanks so much, Frank

Another interesting difference between the 1/2- and 3/4-ton trucks is the way the frame is designed. On a 1/2-ton Chevy the width of the frame inceases until just behind the rear axle. On the 3/4-ton the rails are parallel starting under the cab.

Canadian GMC's of the Advance Design/New Design era ran Chevy motors. I suspect that is part of the confusion above, since we have at least one Canadian in this dialog.

I too have never understood why GMC sold a long box 1/2-ton and Chevy did not. The suggestion that it has something to do with the better GMC motors doesn't make sense since as far as I know Chevy ran the same 216 in 3/4- and 1-ton trucks.

I suspect it was some marketing decision rather than one made based on some engineering issue.

FYI:

SM420s were not available until the fifties ('53 or '54, IIRC). The four speed trannies that were available in that timeframe were of the "Coffee Grinder" variety.

The stanard tranny in 3/4 tons were three speeds. Many people went with a four speed, though.

SM420s became available in 1947. For reference check the Novak page or just google SM420 1947.

SM420's came out with the 48 model year.

Well, color me embarrassed.

I must have misuderstood my grandpa.

My apologies.