1965 chevelle 12 bolt in a 1967 Gto

[keith4909]

My Gto rear diff measured 54.75 from inside backing plate to backing plate. How much narrower is the 1965 chevelle 12 bolt? I'm running 275's on my stock 10 bolt and have about 1.5-1.75 of clearance on both sides. I bought a 65 12 bolt and just curious if I'll need a thin spacer or not? I would measure the 12 bolt but it's being shipped to me.

[andrewb70]

My Gto rear diff measured 54.75 from inside backing plate to backing plate. How much narrower is the 1965 chevelle 12 bolt? I'm running 275's on my stock 10 bolt and have about 1.5-1.75 of clearance on both sides. I bought a 65 12 bolt and just curious if I'll need a thin spacer or not? I would measure the 12 bolt but it's being shipped to me.

Sean,

You should measure from axle flange to axle flange. I believe the 12 bolt and the GTO rear ends will be the same width, flange to flange.

Andrew

[keith4909]

The guy I bought the diff from measured 60.5 inches from wheel surface to wheel surface for the 65 chevelle diff. If it's too narrow is there anything wrong with running a 1/4 or 3/8 spacer to move the wheel out

[TheJDMan]

60.5" is correct for the 65 Chevelle 12 bolt and 1st Gen Camaros. I have one that I modified to run in my Camaro about 40 years ago during a time when these parts were very hard to find unlike today when you can just order one new from any number of sources. As I recall the 67 G-body rear is wider but I don't have that dimension. What ever the difference is divide that by two and that would be the spacer you need or you can use a different wheel with less back spacing. But I would caution you that the 12 bolt has 7/16" studs, I would highly recommend that they be upgraded to 1/2" studs before attempting to use spacers.

[keith4909]

I got a hold of my painter and they measured. It came to 61.5 so it will be .5 inch narrower per side. It appear as if a spacer will not be needed. I'm happy because I'm not a fan of the spacers. I would rather have the correct back spacing.