Ok, you trans guru's. I'm looking to find out what internal differences there are between these trannys are. Sun gear, clusters, clutch packs, servos, case, valve bodies, yada yada. To simplify, what internal parts can or cannot be used from a non lock-up to a lockup type tranny?

TIA.

Troy

Later 904 transmissions (998 / 999) had to big differences:
- Lock-up converter
- Lower first gear (wide ratio)

In general, you can put the low first gear option into a different trans.
If you are after the lock-up feature, it is best to use a lock-up transmission to start with, and beef it up as needed, for your application.