TF999 to NV3550 swap in a YJ
Just finished the swap yesterday. Went a lot easier than I thought, if you have any questions about it let me know.
Vehicle is a 1989 YJ with the 4.2L and TF999 3 speed, NP231
Some things to note that I found out after reading the other NV3550 swap threads:
I used nothing from Advanced Adapters aside from the skid plate mount. My stock 4x4 shift lever fit on the transmission with some modification to the extra bolt bracket that it doesn't need.
Transmission was out of an '03, I used the master / slave, clutch, and flywheel from the same year. The new clutch kit I bought at O'Reiley's had a pilot bushing/bearing combo that is the exact dimensions you need (no need to buy a $23 brass bushing from AA)
Everyone says the master cylinder doesn't fit behind the brake booster... yes, it doesn't but if you drill the holes for it you can set it in at an angle and make it work anyway like I did.
The TF999 is 23 spline output, which is nice because it fits right into the transmission no problem.
The front and rear driveshafts, as well as the auto transmission mount, are the only things that didn't fit back in. The 3550 is longer by about an inch and a half so I'll need some new driveshafts now. It also needs to sit way lower than the auto does. I took my auto mount to my friend's machine shop and he just sawed off the bracket that sticks up over the torque arm. It's a manual transmission mount now!
Other than that, it was a very straightforward swap out. Pictures will come eventually when I get a better internet connection