Th-350

are the tailshaft housings of a TH-350 interchangeable
the one on my wagon looks like a 6'' but
i got one from a truck and it's 9''
and wich torqe converter would be better for performance

the tail shaft housings can be interchanged, but the shaft has to also be changed and that is the last thing to come out of the tranny. you would be better off to change the driveshaft. as for convertors, it should not make much difference, if they are both factory.