1970 differential

Post Reply
ML70
Newbie Poster
Posts: 2
Joined: Fri May 08, 2020 3:59 pm
Location: Chicago

1970 differential

Post by ML70 » Tue May 12, 2020 1:02 pm

I am looking to update the the stock, open rear end in my 70 GS 455. I would like to upgrade to a 3.42 posi rear end. From reading through the forums it appears that I am out of luck at this time as parts are no longer available, is that correct? If so, is there any vendor for a complete axle to axle 3.42 posi 8.5 rear that could be bolted right in? Thanks for any advice.

User avatar
monzaz
Average Poster
Posts: 901
Joined: Tue Nov 13, 2007 7:56 pm
Location: RICHFIELD, OH

Re: 1970 differential

Post by monzaz » Tue May 12, 2020 9:47 pm

yes you are out of luck with the 1968 -1970 Buick 10 bolt 8.25 rear
casting numbers ending in 700 and 724 last three digits
We are all waiting for Fabcraft Metal works to produce the 3.42 and the 3.64 ratios ...but there is no date at this time. :(

So rears that will fit your car are as follows
1967 - 1972 Pontiac 8.2 A-body GTO LeMans Tempest (direct bolt in)
1969-1972 Grand Prix (direct Bolt in)
1971 1972 Skylark or Cutlass 8.5 10 bolt (you will need a drive shaft shortening for this rear)
1968 -1972 chevy 8.2 (chevelle El camino ) will bolt in ...only needs a u-joint swap
1970 -1972 Monte carlo 10 or 12 bolt chevy rear again only a u-joint swap
1968 -1972 12 bolt chevy (chevelle El Camino)
1967-1970 Oldsmobile cutlass 8.5 10 bolt ring with a 12 bolt cover (direct bolt in)
That about cover the rears
early 64-67 rears can be used also but will be narrower and spring perches will be flat and require you to modify to hold spring in place.

Jim
JD Race
J D Race

ML70
Newbie Poster
Posts: 2
Joined: Fri May 08, 2020 3:59 pm
Location: Chicago

Re: 1970 differential

Post by ML70 » Thu May 14, 2020 1:20 pm

Thanks for taking the time to respond Jim, this is very helpful.

Post Reply