Replaced my pinion bearing this fall...but housing was a little eaten up..
so don't expect the bearing to last forever..
want to swap out the entire rear end...sounds easier and probably cheaper...
i've got a 8.25 lim slip...want to upgrade it...posi maybe...
what will bolt right up in place...4x4 rear...r/t..or would a 9.25 fit...
thx

dpoliver

 

posi = limited slip.

Actually Posi = posi-traction = Chevy brand name of a type of limited slip.

r/t rear end = 9.25

I'm not sure on this but the spring perches might be welded on at a different angle for 4wd versus 2wd to align the pinion angle for different heights.

 

i was told that posi and limited slip do the same thing but if you lift the truck and spin a tire the other onewil spin the same way (posi). spin a tire and the other will spin the opposite way (limited slip)

 

posi and limited slip is the same thing.

with posi. if you jack up the rear end and spin one tire, the other one will spin the same way. and if you do a burout you will leave 2 lines

with an open diff. if you jack up the rear end and spin one tire, the other one will spin the oposit way. and if you do a burnout you will leaveone line

 

sticker in the glove box says lim slip...with 3.55 gears...
but a one wheel burnout she does...diff just looks like reg setup...
so does dodge make a lim slip ..open...and a locker type posi differentials ?
in the 8.25 or just 9.25....?
can the 9.25 just bolt right up?

 

your clutch packs might just be worn out.

I have the 3.55 posi too. and when I blew my rearend and I had to get all new internals, it was like night and day. mine always spun 2 wheels, but now with the new rearend it seems to corner better and it will light them up better too.

 

nah it's open...just looks like reg ring and gears...
what model offered the 8.25 posi?
I mean what can I replace mine with...direct bolt in..same drive shaft and all...
just undo the shocks and springs...and swap kinda deal

 

You took your diff cover off and there aren't any clutch packs inside? Just open? If so either someone swapped the glove box (or sticker) or rear axle, or there were some serious QC issues.

The 8.25 was put in the 4, 6, and possibly the smaller V8 Dakotas. LSD was optional in pretty much all.

And one more time, there are three basic types of differentials:

Open
Limited slip aka positraction (chevy) aka sure grip (dodge)
Locker


From Wikipedia:
In the 1950's and 1960's many manufacturers began to apply brand names to their LSD units. The most famous of these was Chevrolet's "Positraction". Since then, Positraction (often shortened to "positrac" or merely "posi") has become a genericized trademark for LSDs.
Other factory names for LSD's include
Pontiac: Safe-T-Track
Ford: Equa-Lock and Trac-Lok
American Motors Corporation: Twin-Grip
Mopar: Sure Grip
Ferrari: E-Diff
Fiat: Viscodrive
TVR: Hydratrak