I was more astounded that with the amount of replies nobody had stated the easiest method of determining how to identify the diff lol

V86BB AAA 364

The 364 part of that code means you have a 3.64 ratio diff, they never made a 3.64 7" (it was 3.62) so you have the correct size/ratio for a RWD Cosworth. However I don't know if it's an LSD or not?

Some info here, although your code doesn't show up.

http://www.super7thheaven.co.uk/Sier...r_Differential