Oh right, didnt realise your Saff was 4wd, well thas easy fixed
If you afraid to spank a Saff youd be out of your mind to spank an 86! Parts, and especially shells, are far more expensive and rare!
Sierra lock isnt the best, but unless you very very good and/or in competition you wont notice it anyhow.
My current drift car (ie one that works

) is a bog standard Volvo 360 with just a welded diff, and i can diff it up in that way better than less experienced drifters (but with plenty of track experience) in quite big spec Cossies, as proven last friday, but it wouldve been the same regardless of car they had, as its seat time that makes you better, not the car.
TBH Sierras arnt too good as standard, but with a few choise mods they get suprisingly good, mostly the mild mods needed to give more front castor and camber (as done to the fast ford drifty shed), then they handle tons better, the FF car is pretty fantastic for a basic car now.