Bro i can help you on this matter as i was also looking for a auto transmission for my G10 carby cultus engine as my current auto transmission got a problem of non shifting, maybe it can be repaired but need a qualified mechanic for that, so now looking for a manual tranny but its hard to change the automatic driving behaviour.
most of the transmissions i ve seen in market were used locally and there is no TCU with any of it, but i ve used it without it so then it tuns out to be semi automatic as the driver have to push the lever to change the gear its like first shift at speed of 20 second at 60, this is what i usually used to do, you need these things too new axles,gear lever, gear wire, brake paddle.
i went to the market one guy quoted me 12k for the auto trans inclusive of old manual trans with no TCU and wiring and one guy quoted me 6k for that but condition was really bad with no TCU and wiring , if your friend's car's tranny is working fine then do contact me before tossing it to the scrap yard guy. as whenever you go to the scrap yard guys to sell your old part they never go above from 2k, 3k, my cars whole engine for 10k but if i want from them its 70k, i really laughed at myself
the real problem arises when you got a faulty part from scrap yard guys as you have to include labor cost which initially installed that thing, then you have to transport that back to the guy from whom you ve brought ( these guys are like when ever you hand over money to them after a problem you goes back to them they say who are you?) and so on, but if you need any further assistance you can contact at 03315990682, i will again visit the market for this sake as my car is standing idle from a month now, then see what comes out as my mind is fighting on the pros and cons of the auto and manual ..