I didnt know that the Sierra ever came as a 2l 4x4.
I remember the xr4i with the v6, they tried a Hart (twin turbo I think) but I never came across that outside Ford R&D, and then went with the cossie - was that a 2l?
Depending on what you are trying to do, remember that the Granada/Scorpio of the period had the same drivetrain so info on that might also be of use.