100 series Diff in an 80 series

Mark,

I think that the axle are different diameters.

Wayne

I do know that ratios are different, so... thats a "no" from me.

Ulises

Depends on what and which...
The front diff centre will interchange...ratio is 4.3 for the 100 as opposed to 4.1 for the 80. The 100 diff centre is weaker because they managed to fit 2 more teeth (43 v 41) on thesame diameter ring gear, hence, thinner gear lands. (Before the 4.3 front diff was put in a 100, it came in a diesel Bundera)
You can run a complete 105 diff in there, but they are wider....bigger brakes, and 5 studs.
The rear diff is interchangeable IF you change the lot....thats right, swap it in and it fits....the centre is completely different as are axle splines, and even the other ends where they bolt to the hub has different bits....the 105 rear diff is a little wider than the 80, and has 5 studs....if you wanted it to retain 6 studs, you need to put your 80 hubs and brakes on the 100 diff and have the axles modified to bolt up.
Ive been toying with putting 100 series hubs/discs and callipers on my 80 front diff to get better brakes (100 is larger diameter disc) or special order slotted DBA discs drilled for 80 but to suit 100 and then use the 80 hub....if that makes sense.....apparently DBA will do that for you.
Andrew