Well I know the Ford 9 inch is an option if I want to get crazy but Id like to keep weight down so is a T2 or 3rd Gen swap with a Kaaz LSD a feasable swap?

 

nope
an 8.8 is an option, an old datsun pickup rear will fit without much problem. (no aftermarket gears available) a Kia sportage front differential is another option...

 

Well crap I had hoped to use a 3rd Gen rear with a Kaaz. I guess Ford 9 inch it is.

 

Biggest problem is fitting a rear-end from a car thats a lot wider with independent rear suspension to a little car with a solid axle. I heard you can put a Miata torsen LSD (or aftermarket Kaaz/Cusco/Mazdaspeed) into a 1st gen rear with a bit of modification and their LSDs are swappable with the RX-2/3 diffs so it should work on them as well.

 

I have the LSD third member from a first gen will bolt right up, that's what I have in mine but u'll need a longer shaft, i use one from an rx3sp and redrill the bolt holes on the flange on the dif. U may be able to use the shaft from the rx7 from which u get the third member from.

 

I used the entire gsl 3rd member from a 83 inlcuding the flange. its a straight bolt-on. And I agree, if you have a non-SP driveshaft, then it will be too short. The non-SP version has a longer pinion shaft.