So after doing plenty of googling on seats that drop into an ae86 with ease I decided to buy some sw20 seats.
Now I've read everything from the bolt straight in, to they need one hole extended, to they need the rails cut and welded.
So I bit the bullet and through my own experience they were a prick to fit with sw20 rails, I had to Redrill both rear mount holes and then once they were in they sat at an angle and leaned in. It was rubbish to be honest, felt so stupid to drive and I hated it lol.
So (I have a point to all this btw) I had a look at the mounts on the 86 seat and they looked like they bolted up at the exact same points. Decided it was worth the effort to pull both chairs apart and see if it would in fact work.
And I can confirm it's an exact fit! Only drilling involved was to add a hole for the lumber support dial. The 86 one sits lower on the back bracket, but there is a smaller hole in the bracket that is in the exact right spot that just need to be enlarged.
I was a bit lazy on the bolt in the back bracket and put a small cut in it to access the bolt instead of trying to get to it under the material. I plan to sew the cut back up now it's done (also cut at the wrong spot first attempt lol)
Will post pics shortly, but in summary fitment is 1000x better and now the seat feels awesome!
Unfortunately the passenger side on the 86 doesn't mount the same as sw20 so it won't be a straight forward job
Hope this info is of use to some people
very nicely done! good photos help a tonne too !