Rear end ID

[cprimo]

rear end has the following 3896838 GM53 87890 and in the 2 o'clock passenger side TDE1211W2 can't find the link to id this rear end, any answers would be appreciated, thanks in advance

[69GWC]

Do you have any pictures of it.
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[cprimo]

Just took it off my '72 to put on my '67 and started the cleaning process. then came nitefall. I went out side and rit down the numbers I saw and figured I would need for one of the many professional classic truck guys would need. So, long story no pics sorry

[GASoline71]

Unless it came out of a '72 C20 (which could have been a 12-bolt, Dana 60, or an Eaton HO)... it's gonna be a 12-bolt.

Gary

[SS Tim]

Originally Posted by cprimo

rear end has the following 3896838 GM53 87890 and in the 2 o'clock passenger side TDE1211W2 can't find the link to id this rear end, any answers would be appreciated, thanks in advance

TDE1211W2

TDE '70 CA10 3.07:1 open
1211 December 11th
W2 Warren Gear 2nd shift

[HotRod C/10]

http://www.gmcpauls.com/67-72_chevy.htm

[SS Tim]

Originally Posted by HotRod C/10

http://www.gmcpauls.com/67-72_chevy.htm

How is this link going to help the OP? While Paul's has a lot of information, the axle codes are only for some 67-68 with the two digit codes.

[cprimo]

So, if it's 3.07 I will be cruzin some really low RPM's with a 700R4 tranny I plan to put in it! Should equate to some really decent gas mileage too, thanks guys.

[SS Tim]

Originally Posted by cprimo

So, if it's 3.07 I will be cruzin some really low RPM's with a 700R4 tranny I plan to put in it! Should equate to some really decent gas mileage too, thanks guys.

Doesn't work that way. It is probably too high of an effective gear ratio in 4th. About 2.15:1. Once you get past that sweet spot where the RPMs are low and the engine is still making enough power your mileage goes out the window as the motor begins to lug. You are going to need different/deeper gears with just about any engine.

[cprimo]

ok then, good to know. I still have the rear from the '67, need to check those gears. it has a straight 6, three speed tranny. The reason I am swapping is the 6 lug rear on the '67 and the 5 lug on the '72 that and the cancer on the '72.

[cdowns]

those numbers tell u what was in there 40years ago

het if you are cleaning it up why dont you show it some love and clean the inside too?? that way you'd know something for sure

[cprimo]

Did that about 5 years ago, had to pull the sludge out by hand! basically thin mud. Replaced it with Royal Purple back then and never put the '72 back on the road, pulled the motor and that was that until now. Was just trying to figure it out without spilling the RP out. Looks like I will do that anyway and replace with Amsoil because I am a distributor now. Where exactly are the numbers stamped inside the pumpkin?

[Stocker]

^^ You can always count the teeth. Divide the # of teeth on the ring gear by the # of teeth on the pinion = your gear ratio.

[cdowns]

havin the rear on two jackstands with the pinion pointing straight down you can check without loosin the grease// should b stamped on the ring gear what the ratio is

or counting is the way too

[cprimo]

New question, I have a '72 5-lug rear end with 3.07 gears and a '67 6-lug with 3.73gears. Can I take the axles from the '72 and exchange them with the '67's? The reason I am asking is I am wanting to change to the lower gear due to the fact that I will be putting a 700R4 tranny.

[SS Tim]

At this point there is no simple solution. Your axle code indicates a '70 MY application. You had it in a '72 truck. It has 5 lugs, so it is likely a wide housing. But it could also be a narrow housing. Here is a link to a thread on housings and in it I placed an axle chart from the GM parts catalog. Read up, then measure both rear ends and their axle lengths, verify ratios in both and look for things like backing plate spacers. Let us know how everything compares.

http://67-72chevytrucks.com/vboard/s...d.php?t=547192

[cprimo]

If not will the gears transfer, pumpkin to pumpkin?

[SS Tim]

Should, but they need to be reset and some people won't do used gears in a different housing. In the end it might just be easiest to set up some new gears and a L/S or locker.