The Stovebolt Site Forums The Shop Area Engine Shop 1962 rearend ratio question

I have searched the forums, and have not found the info that I need. My question is, Where do I find the info on my trucks rearend that identifies what the ratio is? It is a '62 1/2 ton SWB. I believe it was originally a straight 6, with a 3 speed. Did original v8 trucks have a different ratio? I have a friend that has a good rear out of a '64, that was originally a V8 truck. I am wondering if that rear end would have a higher ratio.

Thanks in advance
Mark

The best way is to pull the cover off & count the teeth or look at the markings on the edge of the ring gear or end of the pinion. It will have numbers like 9-41 or 8-31. Divide the numbers to get the ratio. You can count the number of turns on the drive shaft to turns of the drum but if you can,t keep both wheels turning together it gets confusing. Those are two different kinds of rear ends. I am considering the same swap & I think they are interchangable.

Your '62 rearend is probably a 3.90
That '64 could be a 3.73 a 3.90 or a 4.11
They are very different rearends I understand (meaning that the 3rd member doesn't swap out or anything).
Correct me if i'm worng.
Good Luck

Thanks for the replies, guys. I am hoping to get a better highway gear. The original one is not freeway friendly. The '64 rear that I have access to, probably isn't any better that the one that I have. Anybody have any other suggestions?

Some of the v8 trucks had a more highway friendly 3.38 rearend gear. I don't remember where I got these codes but am told they are stamped on the outside of the rearend.

MA 3.90
MB 3.38
MC 3.90
MD 3.90
ME 3.38
MF 3.90
MG 3.90

These were listed for 1961 models. Hope this helps.

Those codes are the same for '62, there also codes MT and MU that are 4.11. the '64 diff would be a Salisbury type, no 3rd member. The housing is 1 peice. For '64 the gear codes are;
WA,WC,WE,WG,WJ-3.73;WB,WF-3.07;WD,WH-4.11. I have been told that some parts will interchange with the earlier diff, but i have yet to confirm this, one day i'm giong to check a Hollander manual on that. 1 note-the '63/64/early'65 12 bolt diff has 17 spline axles,they can be converted by swapping to the 30 spline axle if you want to add a traction aid. There are no 17 spline traction aids for the 17 spline diff.

An easier way then turning the driveshaft is to jack just one wheel off the ground, make an index mark from the pinion yoke to the housing, a mark on the tire (or use the valve stem position) and turn the tire TWO complete revolutions. Counting the driveshaft revolutions will give the ratio.

I,m considering using a 71-2 complete rear end & using 67-70 axles to maintain 6 bolt wheels. Most of those were 3.08. I hope someone will jump in & help us.

67-70 axles are .75" too short.