I see that this has been asked before but I'm finding conflicting information. I recently purchased an 88' vert and have started upgrading it. I know the verts have open diffs.I was able to find and purchase a 4.10 lsd and pinion from an 88 non turbo on ebay. My question is does my car have a 3.9 diff or a 4.10 diff and is the swap as simple as putting the new diff in, or do I need to change the pinion as well?

I've found a few threads here saying all verts were 3.9, and i've found some that say only the auto's were 3.9 and the 5spds were 4.1.

Mazdatrix has this chart:

79-82 3.909
83-84 12A 3.933
84-85 13B GSLSE 4.076
85 12A 3.909
86-88 5-spd All 4.10
86-88 Automatic 3.909
89-92 Turbo 4.10
89-92 non-turbo, non LSD 4.10
89-90 non-turbo, viscous LSD, "GTUs" only 4.30
93-95 w/manual trans 4.10
93-95 w/automatic trans 3.909

but the information there conflicts with what I've read here. Thanks to all who read this and respond.

 

Verts were all 3.909 from the factory. I can double-check yours by running a build sheet if you send me your vin number.

 

PM'd