With these transmisions there's only a couple things to consider.

Stay 98-02 and the only possible issues you have are
Gear ratio (easy to swap yourself)
Internal vs external PNP switch (easy to fix)
Click or threaded cooler lines (easy to fix)

Soo... yeah. You should be able to work right through anything. As for the jy's telling you they won't go into gear. That's a big pile of poop.