Are 8 3/4 posi units interchangeble?

[1968rt]

I have a 742 case with 3:91 gears, cone type sure grip and I have a 489 case  with 3:55 and the clutch type posi. I know I cant swap the ring and pinion, but can i swap the posi units??

[wild383]

As far as I know, yes they do interchange. Check the TECH PAGES section, everything you wanted to know about the 8.3/4" rear end. Willie

[70 Dustpan]

Yes you can.

[d55dave]

I think you have to use the side bearings that suit the sure grip unit, there are two different styles. As above, see the tech pages.

[ski]

Bottom line is yes you can swap the sure grip, you just have to use the bearrings that go with it.  Here's a bunch of reading material.  Some of it is redundent but worth reading a few times.

http://www.68cuda.com/rear.html

http://www.autohobbydigest.com/8_75.html

http://www.geocities.com/MotorCity/Flats/1549/index3.html

http://members.tripod.com/~Mojo_Page/chry875.htm

http://www.moparmusclemagazine.com/howto/155_0308_mopar_rear_end_gears_set_up/index.html