i found a rear end with a better gear and posi unit the guy says it is out of a 442 and it is that funky olds rear end he said. did the 442 share the center pig with the big cars or can i not use this in my 88

 

507OLDS and monzaz are the rear experts here, and hopefully they'll chime in.
The 88 rear is different than 442/A-bodies.
I *believe* the rear for your car should be a 12-bolt (10-bolt cover) 8.875". This would be a Pontiac rear. Full size '65-'70.
If you post pics of what you have, I'm sure "we" can identify it.

 

What type of axel.
My chassis manual of 69' talkes about a O type (most big cars) And a C type (olds chevy dual dealers axel).

You could see this difference in the backplate of the diffhousing.

 

i have the 8.875 12 bolt with 10 bolt cover and this rear that came out of a 442 is the same in appearance i dont know i think even the 390 ring gear will be too much anyways but really wanted the posi unit

 

the manual say with O axel 31 trough 86 series and C axel 31 trough 44 series.
In the 69' manual.

if you got the same axel aperience on your delta I would think it should fit.

could you check if there is a number stamped on the right side of the diff?
Passenger side on the axelshaft.

TO or T3 ? are 3.91 type O lsd diffs same as your delta 88

 

Pics would be most helpful. Especially if you can take the cover off. You could count and read a number of things and be sure of what you have inside. Otherwise, we're guessing.

 

i undrstand the pics will try to get some i know my car has a 2:55 or 2:73 something like that i cant recall right now but it is a tall gear thanks guys for the info see what i can find out

 

just try to get some numbers.
on youre delta you should have 2.56 or 2.96 (455 code QC QI) Std

350 have 2,78 3,08 3,23 ( RA RC RE )

And they are divided in 4 rows Standart or with (JL 2 , J55) Same with the LSD diff

I selve having the RA code on my delta 2.78 standard diff