1963 differential

[Ron L.]

I have a 1963 corvette with a 65 rear in it. The car was built June 28 1963. the bodythe 4th week in june 63. The trans the 3rd week in june. I would like to replace the differential with one that would be right for the car. How do I determine what date would be right? The car is a 340hp car so I think that I read 370 ratio was standard?

[Wayne W.]

Re: 1963 differential

Frankly, I would rather have the later one.

[Ron L.]

Re: 1963 differential

Why? wouldn't like the dates in the drivetrain to match?

[Mike M.]

Re: 1963 differential

waynes reasoning??? probably because the 65 up posi cases are much stronger than the 63-4 posi case.why not get a 63 differential case and put your 65 guts in it. also you can choose which rear axle ratio you want then get a Richmond ring and pinion.. mike

[William C.]

Re: 1963 differential

Well it would be nice, but the later rears were stronger, and had a better system of attaching the front support. The '63 system was notorious for loosening the bolts/elongating the bolt hols in the front support providing a serious "thump" in the rear every time the throttle is mashed. If your goal is a "perfect" restoration (no such exists) then change it out. If you plan to drive the car, keep what you have.

[Jack H.]

Re: 1963 differential

You go by the final assy date of the car (based on the VIN). The power train parts (trans, rear end, engine) came from different GM supplying divisions and were pulled from inventory at St. Louis by rather random draw (no FIFO/LIFO inventory control).

While 'typical' dated part intervals tend to be 4-8 weeks prior to final assy, that isn't a hard/fast rule. The NCRS general policy allows parts to preceed the car's final assy by 0-6 months...

[Ron L.]

Re: 1963 differential

Well it would be nice, but the later rears were stronger, and had a better system of attaching the front support. The '63 system was notorious for loosening the bolts/elongating the bolt hols in the front support providing a serious "thump" in the rear every time the throttle is mashed. If your goal is a "perfect" restoration (no such exists) then change it out. If you plan to drive the car, keep what you have.

I was thinking in terms of value to the car. the car is a driver and not a frame off show car. I was just thinking since the rest of the drive train matched i would look for a correct differential.

[Gary R.]

Re: 1963 differential

As the others said the 65 diff is better then the 63 in terms of durability,however the 65-68 posi's still were not as good as the 69-79 posi's. Many cracked, so who knows what you have in it now. I would take a good look inside if you remove it. There is no VIN on a diff, just casting and assembly dates.The 63-64 had the front bracket holes tapped, used weaker caps,weaker hex head bolts, and of course the very weak Dana posi's or open diff's.
If you're not going to be driving the car much or hard you'll be ok, if you plan on adding some power and driving the car as they were meant to be driven,then you may want to think about beefing it up some.