$350 for an an installed transmission seems like a no-brainer; I mean, the tranny is basically free at that point, and then some. I guess the only way you could lose is if the replacement unit is worse than the stock one. That said, if I was looking at replacing a tranny anyway, I'd be strongly considering one from a reputable outfit like Sun Valley - of course, you're talking much more money at that point, probably 3x what you paid for the car (installed). In your situation, I'd probably go for the $350 tranny.