Good morning,

I need to replace my differential on '77. Automatic, L48 engine, 3.08 greats.

I found a differential from a 1964 Corvette - will this bolt right up to my car and the strut carrier and leaf spring bolt on as well? Gears are apparently 3.36 gears - I doubt I'll notice much of an improvement in off the line.

Thanks in advance for any insight.

Best,

Charley

 

I would advise against a 63 or 64 unit. Very difficult to find replacement parts and most rebuilders won’t touch them.

The 65-66 units are slightly narrower between the carrier bearings and use a nodular iron case whereas the 67 and later use the 3899143 grey iron case.

With your engine, any 65-later unit will work but you’ll need to use a 1330 pinion yoke.

 

Thought as much as when I shop Zip or Ecklers the differentials are for like 1965-1979. Thank you so much!

 

yeah 63-4 diff's were not very good. They can be rebuilt and I just did one but they will require all new internals so unless for a numbers car they are not worth much and would not be my pick to build. 65-68's were Eatons but still had issues, 69-71 are better but the 72-79's would be my choice to build.
Now if you are just looking to swap in a used diff I would be very cautious about that as many used diffs have issues and you don't want to install one that is going to give you a problem. If possible look at it with the cover off, oil out and spray the posi case with brake cleaner looking for cracks.

 

my personal experience is it will work and last as long as you dont like to race it or abuse it at all. I take mine to the drags a few times a year and I put in a 64 3.70 rear end last year. It drove it pretty hard last year with oabut 400hp and maybe a lap at the track. this summer had about 500 hp in front of it and had it at the track a few times and drove it like it was rented. I ate up the spider gears about a month ago I think. The posi carrier is still solid, no cracks and the gears are still perfect which I will be reusing, the rest is going up for sale for any C2 guys that need the numbers. I am replacing all that with a 69 case.

My point is how are you going to drive the car and what kind of power is in front of it. If you are a cruiser and never get rowdy it will last you and you can rebuild the old rear end while you are still cruising the 64 rear end. Especially if its cheap...... But if you like to get excited off the lights then you may want to keep shopping. 3.08 complete rear ends are plentiful on facebook, c list and ebay at reasonable prices. Its the taller gears that are hard to find or are stupid expensive like 3.70s and 4.11s now that everyone is running a 5 speed.
Other things are the 64 snubber isnt reinforced around the bolt holes and you can possible tear the snubber right through the bolt holes.....i did that too. But your original 79 snubber will fit. Externally all the parts will swap over. Another bad thing is the spring pack inside the posi was a weird piece as it had alignment arms bent into the end of the pack to keep it aligned in the posi case. Those little arms can break off and land in the bottom of the case. I pulled a couple of them out of the case when I first got it. I pulled the cover and drained it to inspect it and found those little pieces. They are about a half inch by and inch and an 1/8th thick. Luckily they never made it into the spiders or side gears.

I can post a pick of the carrier if you want . The 65 and later Eaton carriers look cast and have rounded ends and bigger round access holes. The 64 cae looks machined and has alot of sharp angles and square opennings that tend to lead to the cracking that GTR mentioned

Good hunting