Difference in pre 84 frames?

[GBodyWarpony]

New to G Body scene. I have a 81 Cutlass and i have heard of differences in cars built before 84.?? What all is different on pre 84 cars? Thanks in advance

 

[L92 OLDS]

New to G Body scene. I have a 81 Cutlass and i have heard of differences in cars built before 84.?? What all is different on pre 84 cars? Thanks in advance

The primary difference is the transmission mount added in 1984 for the 200 4R trans crossmember. The 1983 Hurst Olds also had this bracket.