boost monster

I got this box from a big spec zetec turbo. It has a 1994 date stamp on the casing but is fitted with an rst lsd.
- Will this be any better than an rst box?
-How do I tell if its fitted with IB5 internals?
-What is the thing on the speedo drive?

Twins

iTrader: (18)

Bit on the speedo drive is just what the efi cars had from the factory