I'm sure this has already been adressed multiple times, but i can't find it

So i'm buying a 13b out of a 85 rx7, is it a direct swap into a 79 rx7?
And i'm thinking about doing a rear end swap because the rear end on the 85 has lsd, mine doesn't. does lsd make it faster? or is it a waist of my time? and is that a direct swap?
Kurt

 

you need a se front crossmember if you want it to drop in real nice. you could also bend up your engine mount bar and make it work but i would recomend the se front.
lsd just allows for beter traction, faster but no hp.

 

If the 85 you're getting has a 13B it's a GSLSE. which means the lsd in the rear has 4.10 gears instead of the 3.90s in your car. Swap it in and it will make your car a little quicker through the gears.

Worth while imop.