I have an 87 GTA and i just dropped in a 383. my problem is that the stock tranny filler tube will not fit flush with the trany, so it constantly leaks. has anyone dealt with this problem or know of an after market tube that will fit?

The tube should fit fine, but I know I struggled with mine. Did you make sure the rubber gasket/ring was still in place at the tranny? It should go around the fill tube about an inch or so as it fit into the tranny. Also, did you bolt the tube bracket back up to the motor/transmission? I know I struggled with getting mine to fit in for both of those reasons, but had no issues with leaks on the 700r4 or the th350 on my last swap.