9 inch is WAY to big for what hes after
Id almost be inclined to put a KE30-55 diff in, locked centre and that would be up to the task. If not other options are hilux, R31, commie, prado. But these will all need more work to fit than the KE30-55 diff
I'm running a shortened hilux with a locked 4.11 centre, currently making 211rwkw and thrashed everytime i drive the car and i havnt had any problems with it, its been the in car for almost a year now. I did hav clearance issues (diff hitting bump stop, removed bump stop and diff hit the floor) until i fitted stiffer rear leaf springs, after i havnt had any issues. Hasnt hit once since then