This isnt an ls1, but you guys know your crap.

72 Chevelle with a 700r4 swap. Swap was a stock trans, TCI SS Fighter converter. Everything bolted up, checking it while on jack stands. Rear wheels get power in every gear including neutral (im talking rear wheels spinning 15-20 mph in neutral), and my rear brakes get overpowered by the wheels and I can't get them to stop turning.

Any ideas or help? Some search on other boards are showing a TC problem might cause both, but i'm not sure..

 

Your linkage may not be adjusted properly. The shifter you have may or may not work, 3 speed vs 4 speed. I'd start with the shifter and trans both in park and then hook up the linkage. Second the TCC needs to be ran through the brake switch with a relay to work correctly. There are also manual kits available. Search, sallee 4l60, their instructions cover it very well.

 

Should have mentioned, that was with it being shifted at the trans manually. No linkage hooked up yet