yes there was a B&W rear in the 87-90 irocs but it was a 7.75" ring gear. wow what an improvement .125"!!!!!
and to top that off you CANNOT find parts for them, unless you have a few as spares, AND theres only THREE ring gears for them 3.27, 3.45, and 3.70.
not too much of a selection is it?
p.s. the 3.70 from GM is $1150.50 canadian (it was last time i checked)