The Stovebolt Site Forums The Shop Area Engine Shop 49 chev 3/4T pu rear end

Was the original rear end on a 49 chev 3/4T p.u. a closed or open driveline? The one I just got is open with 3 u-joints and a carrier bearing in the middle, more or less. The diff is a 10 bolt with plate that removes out the rear and pumpkin that removes( 10 bolt) out the front. Wonder what the r&p ratio is? Will the rear end in the 55.2 1/2T p.u.(6 lug), that I got in a trade for some stuff, fit the 49? I'm already putting the front end out of the 55.2 1/2T in the 49 anyway( also 6 lug). The 55.2 rearend is also a 10 bolt, rear plate and pumpkin, looks identical to the 49, sorta.

You can bolt in a later carrier (same from '46-'72 3/4 ton only) with 4.11 or 4.10 gears. Look for a big block truck with automatic, they used the 4.10 gears. The half ton differentials will not work. If you can find the carrier with the gears you want, it's an easy swap. There is an article in tech tips.

If the rear end in the truck is original, it is either 4.57 or about 5.10. I think the 49 had the same driveshaft as my 52, front half closed, rear half is open.

You can put the 1/2 ton rear end in, sounds like it's set up for the open driveline. You will probably have to get a crossover u-joint, I think they used different sizes between the 1/2 & 3/4 ton. Most parts stores should have one. Just take in both joints and tell them what you need. You might have to do some work with the spring perches, don't know for sure.

If you go to the tech tips section, you can find instructions on how to determine your gear ratio.

Standard ratio for your 49 3/4-ton rear is 4.57 with an optional 5.14, same as 1-ton. Most were 4.57. Does it have a 3-speed or 4-speed? Not likely that a 3-speed truck would have the steeper ratio rear. Original 49 would have a closed (torque tube) front drive shaft to a carrier bearing with open rear shaft. 2 u-joints visible as the front joint is enclosed in the ball-and-socket on end of transmission. 3/4-tons were like that thru 53. 1-tons had all open u-joints. I guess your sure it's a 3/4-ton? 3600? pickup bed 7 1/2' long? It may have had a 54 or later transmission/ drive shaft swap already.

Frank50
The bed is 108" long, 50" wide. The wheelbase is about 136" long. The trans is a 420 with a pto outlet(cover plate on it) on the driver's side. The running boards on it are 84" long, this 49 chev is, I would guess, about a foot or so longer than my 54 gmc 1/2T. I can see 3 u-joints with a carrier bearing very easily. Are 1 tons not duallies on the rear?

just found American Classic VIN Decoder. This thing comes back a 3800 series. I guess that's a 1 ton? GVW on vin plaque in truck is 8800 and the am. classic decoder says the same. Hmmmmm :confused:

You're right. That wheelbase is a 1 ton. Gear ration should be 5.14. Basically the only difference between the 3/4 and 1 ton is the wheelbase, heavier frame and springs and gear ratio.

One ton pickups are a little rare. Good score! The later pumpkin (from 3/4-1 ton truck) may well be your most economical ratio upgrade.

Cool 1-ton pickup. You have a Model 3804. 3800 being the series and 04 is the pickup (dispatch) box or bed. The dual rear tires were an option and lots of flatbed/stakebeds had them. I never saw an original "dually pickup" from that era. Don't think they made them. That would be cool with extended fenders. Does it have the original 17" wheels? The frame is quite a bit heavier than a 3/4-ton, as well as the axles and springs. That's how you can have an 8800 gvw vs. a 5800 for a 3/4-ton. I agree with Splashoil, good score! :p

harry,check the salvage yards and keep a good eye out when you are driving through the farm and ranch land for 1968-1972 3/4 and or 1ton GMC's and Chevy trucks espicaly ones with an auto transmission. there's a good chance it will have a 4.10/4.11 pupkin in there and maybe you might hit the gold mine and get a 3.73 or a 3.08 pupkin, those two are really hard to come across. the swap is really easy.

tony'n weatherfor(1010 kilometers to you east} just doesn't sound right.

There is a 4:10 third member on Ebay right now from a 67 - 72 Chevy 3/4 ton - # 7900609800 (sorry dont know how to link). There is only 1 day left so hurry. I was going to consider this swap for my 48 - 3/4, but I dont want to pay the shipping on something this heavy. Not even sure that this is the right one. Good luck anyway.
Ralph

Decent price, but shipping will kill you. I bought an entire differential on the 67-72 board that was close enough to pick up. Gave $100 for it. http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=7900609800
http://67-72chevytrucks.com/vboard/...ea0aaa48d13f71075cdd374128&forumid=8

Still, after shipping, compare with new gears and installation $$$$$.