Nope, as said all cosworth beams are the same geometry, 2wd or 4wd are all 18 degree, the 2wd beam has a slightly (1/2") wider diff carrier.

The 6 degree beam is achived by modifying the pick up points for the trailing arms, and the arms are altered as well. Have a search for threads on here about them, and why it's such a vital mod.