Just like the rest of a supra, there is a nice, easy to follow instruction book for the V160, which is pretty much an idiots guide to repairing one.
I pulled my V160 apart back at the start of summer to work out why it had a dodgy5-6th change, to find the cause of a tiny whine at cruise, and to reseal the casing which was leaking.
Using the guide I was able to change a worn input shaft bearing(the cruise whine). I checked all the gears/synchros etc for wear/clearances. Replaced the broken pivot pin in the shifter arm directional reverse linkage(dodgy change). Finally I checked any clearances I could without full dissasembley and put it all back together with all new shaft seals and sealant on the case flanges.
You will need a press and various different 'dies' for getting it apart. Some of the gears require quite a long throw, long jawed/toothed puller to get them off. I also needed to buy a 41mm 12 sided socket to get a lock nut on the end of the V160 layshaft off. Other than thst it's just a certain amount of care and mechanical competence required to service one of these things.
Saying that I don't recommend everyone now goes home and pulls their box apart. You've got to be willing to accept it may well become expensive, when you get something wrong. The parts are also very expensive for these boxes now, and not 100% are available until someone starts (maybe) producing replacements.