Thanks for the comment!
Well I finished slapping back the T50 together...
...right in time to forget it in the far end of the shed as a backup in case the K50 isn't up to the task... sad because it was pretty clean.
And as soon as that was finished, I charged ahead into the K50 inspection/rebuild... with no FSM...
Scratched my head a little, but after figuring out everything, I am impressed by this little tranny. I have never worked on a weird tranny like that though. The design is impressive, how everything was created to be as compact as possible. The reverse gear has no selector, actually the reverse gear on the output shaft is cast on the 1st/2nd gear selector so is always turning with the output shaft. The countershaft reverse gear is also always engaged so to engage the reverse gear, the "idler" gear is attached to the shifting rod and moves to mesh between the 2 other gears when reverse is selected... really weird but compact. The 5th gear lives in the extension housing where the reverse gear on a T50 normally is. Thing is that to engage properly with the standard H pattern, it needs a weird linkage to inverse the shifter movement that pulls on the rod but the selector need to move forward to engage 5th gear... and to be sure that there is no slop in there, their is 2 eccentric bolt to adjust everything perfectly... anyway, it's weird and beautifully thought at the same time.
But the thing that surprised me the most was that I was able to strip the hole tranny, shifting rods and both input and output shaft with only a hands full of tools : 12 and 14mm wrench, a pin punch, a hammer, flat and philips head screwdriver and a pair of c-clip pliers... no gear pullers or press, no SST... you could rebuild the whole tranny in the bed of a pickup truck in the middle of freaking nowhere with the basic tools that are hiding behind the drivers seat... awesome!
So the verdict : synchros are brand freaking new. Input and output shaft bearings are the same as the ones in the T50 and are new too, no slop and spins like butter. Both input and output seals are also the same as the T50 and I already have a new pair waiting. All the gears are in perfect conditions. The only parts that will need replacing is the front countershaft bearing and the shaft that goes trough the counter shaft. Luckily, that shaft is only 46$ from toyota and the needle bearing can be replaced by a SKF bearing worth 30$. I'll also need to replace a circlip that has seen better days and a couple bolts... all in all I have less than 100$ of parts to bring it back to new condition... not to bad!
And here is the ****ty part... don't ask me how I did this... the 5th/reverse linkage is held on the case with 2 countersunk philips head screws... piece of crap for everyone who has taken apart an oil pump and the likes, half of the time the stupid bit slips and strips the head... not in my case...
The stupid bit shattered in a thousand pieces... and it wasn't a master-crap bit, trust me. So now 3/4 of it is still stuck in the head and sure enough it stripped while shattering so it won't come out.
Luckily those screws are worth 0.76$ from toyota... I'll have to weld the shattered bit in the hole to be able to pull the last bit of linkage left in the case, than I'll order my parts on monday and get everything cleaned good to be able to slap everything back in the case when parts will arrive.