i have a 3rd gen trans am rear end, the 1986 axle is 61'' wide and came with a borg warner 7.75 inch and 3.27 gear and disc brakes
the borg warner 7.75 is supposed to be pretty tough, i know it will the spin tires as long as i stay on the go pedal
the 3.27 ratio also gets me 20 mpg on the highway with the 700r4 and ramjet 350
i used the sway bar and torque arm that came with the rear axle mounted flipped on stock springs
the sway bar makes truk handle like a go cart
and the torque arm eliminates axle wrap
with wide tires it is pretty tight, but i have never rubbed a tire on the fenders
3rd gen camaro is the same width but has drum brakes and corporate gear ratios from 3.08 to 4.10