The Stovebolt Site Forums The Shop Area Engine Shop 3600 Rears - 3:73?

I put a 4:11 rear in my '51 3600 and it sure has been a help. However, I have been told that there are some 3:73's around, though rare. My understanding is that the '67 to 72 big Chevy vans are the ones that have punkins that drop right in and a very few of them had 3:73's. I searched online for the 4:11 I have in my truck, but I think I just lucked out. In order to increase my chances of getting the right rear end this second time around, I need to know what model van to look for - G20? G30? All I know is that it has to be a 3/4 ton chassis. Anybody know? Anybody know what other vehicles used the same punkin? Maybe if we all put together what we know, we can all tour down the highway at 60 and still hear the radio.

I think 3.73s or 3.90s could sometimes be found in 3/4 ton suburbans as well. Probably more likely 3.90s, though I am not certain. A search may turn up some more info here.

The guy that ran the junkyard, 40 years ago, used to have books that listed interchangeable parts. With all our computer and networking capability these days, isn't there a database somewhere that does the same thing, i.e. parts interchangeability listings? I’ve only been to the junkyard a few times in recent years, but I’m positive I saw the guy crosschecking numbers on his confuser. Is this something they subscribe to, or software they buy? Most likely it’s out of the reach of the average homebuilder/restorer/hot rodder, as far as cost is concerned?
Roy, you said the 4:11 pumpkin from a later ¾ ton dropped right in correct? I wonder if one bought a 4:11 or 3:73 gear set from Chevy if it could be installed in the 1950 carrier? Don’t we have any Chevy parts guys on the forum? When I was a Chevy parts man back in the 60’s we had a pretty good idea of what would interchange with what. Are there any of the earlier Chevy Parts manuals available on line? Like 50’s through the 80’s?
Denny Graham
Sandwich, IL

Bare Bolt, I thought that the 3600 came with a 4.56 gear ratio originaly. I could be wrong and am sure someone will correct me if I am.

IIRC, you could order a 3/4 ton pickup with the following gear ratios starting sometime in the sixties.

The ratios are:
4.55
4.11
3.90

Most trucks were 4.55's, but on the automatics, they generally did 4.11's. 3.90's were available by request, IINM.

There were aftermarket kits available with 3.73 gears, but I do not know who made them.

The standard for the 3600 3/4 ton was 4:57 according to my handy dandy factory spec manual. You could order a 5:14 if you were planning on pulling some really big stumps. The one ton came standard with the 5:14 and the big boys had 5:43s and even a 6:17. With a 6:17 all you would need is a blade to make it a bulldozer.

You wouldn't find any 3/4 ton parts on the early Chevy Van as the were based mainly around Chevy 2 (Nova) drivetrain parts until the '71 model year. Might be able to check the P series step van, but I think that they only had the same gearing as pickups. Also, none of my guides show a 3.73 or 3.90 in 3/4 ton. I have heard of an aftermarket 3.90, but I don't think that they are being producad currently.