In the summer i intend to buy a MK indy kit, but in the mean time i am on the lookout for the donor parts, i intend to have a bike engined car(not quite made up my mind on which one) it will have a LSD and have disc brakes front and rear, my question is, which of the sierra car(s) do i get the parts from, i would be very appreciative if you could advise me on the engine size/year/model of the cars i need, can i also get all the parts from the same car, and what the best ratio LSD

Welcome to the site

If you want an LSD you need to get a 4x4 sierra, they also have rear disks. But the front uprights wont be any use to you. But you can easily get a couple of normal sierra front uprights.

AFAIK the LSD only came in 1 ratio...not sure though.

Cheers,
David

As has already been said you need the rear end from a 4x4, the diff ratio is 3.62 and it's LSD.

HTH,
Rich.