i am thinkin of picking up a disk rear end tomarrow. my question is what gear ratio is most common?? i currently have a 83 l69 with 3.73's but drums. the disk rear end is a posi unit out of a 90's gta and what is also needed to do the swap?

 

'87 GTAs all should have been built with 3.27:1. '88-'90 should be 3.27:1 or 2.77:1, unless fitted with the LB9 / T5 combo, then 3.45:1. '91-'92 should be 2.73:1 or 3.23:1, unless LB9 / T5, then 3.42:1.
Grab the proportioning valve and the e-brake cables if you can.
Also, grab the sway bars. They're better than what your '83 had.

 

ill see what i can find... i dont think it has the ebrake cables?