I disagree in regards to that last post, about the M-21 or M-22 being such a good transmission they are not that good at all.
A few people have told me that the cases on those aluminum transmissions have a tendency to bust or crack easy, they are just a thin aluminum case.
I personally don't understand why they sell for so much money, the cheapest M-22 or M-21 I heard about that sold went for $350.00 and even that is too much those units don't even come with overdrive so your not saving any fuel with them.
However its possible to add overdrive it's available on them now but again it's not worth it, one guy told me that they run about $1800.00 to add on.
