Rear Axle Ratio Charts For 1967 - 1972 GM Trucks

['68OrangeSunshine]

Originally Posted by badpeanut

i have a 1970 leaf-spring 6-lug 3:07 posi, which is "tpo 0422". I decode this as:

• tpo=ca 10 3.07 posi
• 0422=april 22

what is the meaning of ca vs ce?

at first i thought it might be leaf spring rear suspension vs. Coil spring rear suspension, but i see the same with k-series so this is ruled out.

CA = [2wd] ALL.
CE = '' V8
CS = '' L6
CM = '' V6

[LockDoc]

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I just wanted to thank everyone for adding to the thread and say that I'm glad it is still helping people out.

LockDoc

[dlyons321]

This is one awesome thread! So the stamp on my axle is TPR 0612w2 E. It is decoded as either 1970 KE 10 3.07 w/ posi or 1971 G-10 3.36. The gears are 3.07 I can confirm but not with a stamp, rather an engraving where the stamp usual is. This is a 12 bolt unit.
Is the KE designated as 4 wheel drive rear end?
Any literature on decoding the casting #s on the outside of rear end? #3896839
My truck is a 1970 k10 swb. Im curious id that 12 bolt was an option on a 1/2 ton truck. The SPID does not say that. Most likely added later by previous owner?

['68OrangeSunshine]

Originally Posted by dlyons321

This is one awesome thread!
Is the KE designated as 4 wheel drive rear end?

Yes. Specifically K = 4WD [C = 2WD, but you knew that.]
E = Eight cylinders.

Other designators are -- KS, KM, KA.
S = Six cylinders [L6]
M = Six cylinders [V6]
A = All trucks.

Front wheel drive [only] was not an option in this era. All vehicles were primarily rear wheel drive. Front wheel drive assist was actuated by locking the hubs. You have to get out of the truck, stand in the mud, stoop down and twist the levers on each side to engage.

The Corporation 12-Bolt differential was standard on all 1/2 tons.
[There may have been ''Heavy Half'' variations optioned, but I won't get into that. ]

dlyons321 -- Is your truck an automatic? Manual gearshift trucks got 3.73. Automatics got 3.08.
3.36 is an unusual ratio for a pickup.
G/10s are 1/2 ton Vans iirc.

[dlyons321]

Originally Posted by '68OrangeSunshine

Yes. Specifically K = 4WD [C = 2WD, but you knew that.]
E = Eight cylinders.

Other designators are -- KS, KM, KA.
S = Six cylinders [L6]
M = Six cylinders [V6]
A = All trucks.

Front wheel drive [only] was not an option in this era. All vehicles were primarily rear wheel drive. Front wheel drive assist was actuated by locking the hubs. You have to get out of the truck, stand in the mud, stoop down and twist the levers on each side to engage.

The Corporation 12-Bolt differential was standard on all 1/2 tons.
[There may have been ''Heavy Half'' variations optioned, but I won't get into that. ]

dlyons321 -- Is your truck an automatic? Manual gearshift trucks got 3.73. Automatics got 3.08.
3.36 is an unusual ratio for a pickup.
G/10s are 1/2 ton Vans iirc.

Orange,
I understand everything other than the 12 bolt coming standard on 1/2 ton trucks. I have been under the impression that 1/2 ton got 10 bolts and 3/4 ton got the 12 bolts.
My truck is automatic and has Dana 44 with 3.07 gears in the front.

['68OrangeSunshine]

Originally Posted by dlyons321

Orange,
I understand everything other than the 12 bolt coming standard on 1/2 ton trucks. I have been under the impression that 1/2 ton got 10 bolts and 3/4 ton got the 12 bolts.
My truck is automatic and has Dana 44 with 3.07 gears in the front.

You may have it backwards. Some 3/4 ton diff had 10 bolts and the FF had 14.
Later than 67-72, S/15s had 10 bolt diffs, but that was coincidental and another type.
The 12-Bolt Truck rearend was different from the 12-Bolt Car diff, too.
I'm not expert on the EATON and HO52 rears. They were 3/4 ton iirc.

[dlyons321]

ahhhh I got it now. I apologize I'm a recovering square body guy. I bought this truck in July and I'm just now getting some real time with it. Thanks for your help!