Replacement gearbox problem

[svxistentialist]

My Dec'91 car imported from Japan has a tranny problem. It is constantly pulling 3rd gear, no other gear[except reverse] works, and it will eventually cook the clutch.
I have found a '95 box I can fit relatively cheaply. Can anyone tell me if there are major difficulties or differences between the '92 and '95 box that I would need to be aware of before purchasing the box?
The '95 box should have the modifications and the stronger torque convertor [although the torque convertor in my box is OK], so I would expect to get good service from the change.
Whatever fix I implement, I intend adding a supplementary parallel plumbed cooler and an in-line filter to keep cooling up to scratch. Also will fill with Redline Hitemp oil.
Then I will give the car a serious work-out. Goody goody, as Hannibal Lecter might put it.
Any advice on the box fitment appreciated.