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66-PMD-GMC · 12-18-2013, 09:15 PM

OK,
I am in the midst of 3 builds at once and I am pulling my hair out on one of them.

I have a 62 GMC that is a ground up deal going.

The original differential was broken. I got a diff out of a 70 and tried to install it but the trailing arm perches are in the wrong place.

The owner decided he wanted to go 5 lug so I ended up getting another "good" diff off C/L ...

This diff started leaking from the axle tubes the minute I put fluid in it.. the center section casting is cracked!!!

I pulled the posi carrier and pinion out, all in good shape.. but the axles don't match any other 12 bolt I have??
I have the axles out of the 70 diff but the axles out of the leaker diff are longer...
Anyone know how many length 12 bolts were put into Chevy trucks and what years had what lengths???

12-18-2013, 09:15 PM	#1
66-PMD-GMC The 60-66 GMC/Pontiac guy.... Join Date: Oct 2010 Location: Apache Junction, Arizona Posts: 1,306	12 Bolt Differential Mystery OK, I am in the midst of 3 builds at once and I am pulling my hair out on one of them. I have a 62 GMC that is a ground up deal going. The original differential was broken. I got a diff out of a 70 and tried to install it but the trailing arm perches are in the wrong place. The owner decided he wanted to go 5 lug so I ended up getting another "good" diff off C/L ... This diff started leaking from the axle tubes the minute I put fluid in it.. the center section casting is cracked!!! I pulled the posi carrier and pinion out, all in good shape.. but the axles don't match any other 12 bolt I have?? I have the axles out of the 70 diff but the axles out of the leaker diff are longer... Anyone know how many length 12 bolts were put into Chevy trucks and what years had what lengths??? __________________ Building Genuine Pontiac Firepowered cars and trucks for several decades. Why Pontiac?? That's just me daring to be different. Projects.. 63 C10 Short Wheel Base fleetside (The Pro-Street) currently under reconstruction. 440CID 2X4 Pontiac Last edited by 66-PMD-GMC; 12-18-2013 at 09:21 PM.