What do you mean by 2nd gear is toast? Does it just slip out of 2nd gear or does it not go into 2nd gear? Most of the time it is the shift fork that is the problem, it gets bent therefore causing shifting issues. Only thing you can do is tear into it and fix whatever is wrong, wether it be a shift fork, 2nd gear itself, clutch.... Cant tell you if any other transmission will fit that bike. If it shifts hard into 2nd I have also seen the gear selector mechanism bent and that's a cheap easy fix. Download the manual off here....