How to determine rearend specs.

[70' Chevy]

Someone give up some good tips on how can I determine what rearend the old truck has. I know it has 10 bolts in the cover (if i didn't miss any under the grime) but that is about all I know at this point. It needs a heavy duty degreaser and some high H2o psi. Sounds like it is geared low when running thru the gears. Also if it's a posi track could I jack it up and roll one wheel clock wise and the other go ccw or does it work differently?

[Americanrider]

Since it's dirty clean it all the way and pop the cover, inspect & count the teeth, do the math, check wear pattern, wipe out all the sluge from the bottom of the housing, re-seal and re-lube. The only way to be sure what you have and what shape it's in. The general rule of thumb is most Chevs got Eatons and GMC's got the Dana 60, but there are exceptions to this rule. The Dana 70 is a Dually Rear from newer trucks, I just threw that in there to confuse ya.... Welcome from Rainy Washington state!

Note: DANA 60 top right, DANA 70 top left

[Old Yeller 1970]

There is also a three letter code (for the axle ratio) stamped on the front of the right axle. Only, problem is I can't remember what ratios go with what letters. Maybe someone else on the forum has that info. Once you clean up the axle you might post it and see.

Of course if someone has already changed the gears you'll have to follow American's advice anyway.

[Palf70Step]

These are the axle codes 1970 Chevy. I am not sure if they apply to other years or not. I can't rememmber where I found them, but maybe this will help.


Series-Code-Ratio-Plant
1/2-Ton-TDA-3.73:1-N/A
1/2-Ton-TDB-4.11:1-N/A
1/2-Ton-TDC-3.07:1-N/A
1/2-Ton-TDD-3.07:1-N/A
1/2-Ton-TDE-3.07:1-N/A
1/2-Ton-TDH-3.73:1-N/A
1/2-Ton-TDI-3.07:1-N/A
1/2-Ton-TDJ-4.11:1-N/A
1/2-Ton-TPF-3.73:1-N/A
1/2-Ton-TPG-4.11:1-N/A
1/2-Ton-TPH-3.07:1-N/A
1/2-Ton-TPI-3.07:1-N/A
1/2-Ton-TPJ-3.07:1-N/A
1/2-Ton-TPL-3.07:1-N/A
1/2-Ton-TPM-3.07:1-N/A
1/2-Ton-TPN-4.11:1-N/A
1/2-Ton-TPO-3.07:1-N/A
1/2-Ton-TPP-3.07:1-N/A
3/4-Ton-TAA-4.10:1-N/A
3/4-Ton-THU-4.10:1-N/A
3/4-Ton-THV-4.57:1-N/A
3/4-Ton-THW-4.10:1-N/A
3/4-Ton-THX-4.57:1-N/A
3/4-Ton-THY-4.57:1-N/A
3/4-Ton-TIA-4.57:1-N/A
3/4-Ton-TIB-4.57:1-N/A
3/4-Ton-TJS-4.57:1-N/A
3/4-Ton-TJT-4.57:1-N/A
3/4-Ton-TJU-4.10:1-N/A
3/4-Ton-TLN-4.10:1-N/A
3/4-Ton-TMZ-4.10:1-N/A
3/4-Ton-TNA-4.10:1-N/A
3/4-Ton-TNB-4.10:1-N/A
3/4-Ton-TOU-4.57:1-N/A
3/4-Ton-TOT-4.10:1-N/A
3/4-Ton-TTF-4.10:1-N/A
3/4-Ton-TWI-4.10:1-N/A
3/4-Ton-TYS-4.56:1-N/A
1-Ton-TID-5.14:1-N/A
1-Ton-TIE-4.10:1-N/A
1-Ton-TIF-5.14:1-N/A
1-Ton-TIG-4.57:1-N/A
1-Ton-TIH-4.10:1-N/A
1-Ton-TLJ-4.10:1-N/A
1-Ton-TLV-5.14:1-N/A
1-Ton-TLW-4.57:1-N/A
1-Ton-TLX-4.10:1-N/A
1-Ton-TLY-5.14:1-N/A
1-Ton-TLZ-4.10:1-N/A
1-Ton-TMC-4.10:1-N/A
1-Ton-TMR-4.10:1-N/A
1-Ton-TMX-6.17:1-N/A
1-Ton-TNW-4.57:1-N/A
1-Ton-TNZ-4.10:1-N/A
1-Ton-TRN-4.10:1-N/A
1-Ton-TVF-5.14:1-N/A
1-Ton-TVI-5.14:1-N/A
1-Ton-TVL-4.57:1-N/A
1-Ton-TVM-4.57:1-N/A
1-Ton-TVN-4.57:1-N/A
1-Ton-TVO-4.57:1-N/A
1-Ton-TVS-5.14:1-N/A
1-Ton-TVT-5.14:1-N/A
K1/2-Ton-TDF-3.73:1-N/A
K1/2-Ton-TDG-3.07:1-N/A
K1/2-Ton-TDH-3.73:1-N/A
K1/2-Ton-TDI-3.07:1-N/A
K1/2-Ton-TDJ-4.11:1-N/A
K1/2-Ton-TPK-3.73:1-N/A
K1/2-Ton-TPL-3.07:1-N/A
K1/2-Ton-TPM-3.73:1-N/A
K1/2-Ton-TPN-4.11:1-N/A
K1/2-Ton-TPO-3.07:1-N/A
K1/2-Ton-TPP-3.07:1-N/A
K1/2-Ton-TPR-3.07:1-N/A
K1/2-Ton-TPW-4.10:1-N/A
K1/2-Ton-TPX-4.10:1-N/A
K3/4-Ton-TGA-4.57:1-N/A
K3/4-Ton-TGB-4.57:1-N/A
K3/4-Ton-TPW-4.10:1-N/A
K3/4-Ton-TPX-4.10:1-N/A
K3/4-Ton-TPZ-4.57:1-N/A

[kingsolver72]

Palf,that great info.

[Old Yeller 1970]

I knew someone was bound to have the codes, Thanks Palf.

[72 longhorn BB]

Can you please be a little clearer on where to find this stampig on the right axle?

I can not see mine

[Palf70Step]

I could never find mind either. I think the rust and grease ate mine.

[Old Yeller 1970]

On my truck, I jacked up the rear end and crawled under it, in front of the rear axle. Then looking to my left about 10" from the pumpkin it was stamped on the axle facing straight toward the front of the truck.

There's no guarantee all of them were done that way but on mine it was right where the mechanic told me to look.

[70' Chevy]

Thanks for the codes they helped! Had trouble in locating it but at last I found it stamped on top of the pumpkin on the drive shaft side. Palf, you & 72 Longhorn may want to check there. The code on it was a THU 4:10 version.