wont shift to 5th and pops out of reverse
#2
Are you sure it is the mazda box? Many 80's trucks came with only 4speed trannys....
Anyway, could be a lot of things. If 5th and reverse are mostly affected, then the actual shifter could be bent or otherwise mis-aligned. While I haven't head of bad fluid locking out gears, it can cause grinding and slipping out of gear, from too little/too much fluid. Check that, take the fill plug out. If fluid comes out, note it's color and any grittiness. Looking for a red-brown color. Black indicates it needs a change. If no fluid comes out, drain whatever's in there and refill with plain old mercron ATF.
Anyway, could be a lot of things. If 5th and reverse are mostly affected, then the actual shifter could be bent or otherwise mis-aligned. While I haven't head of bad fluid locking out gears, it can cause grinding and slipping out of gear, from too little/too much fluid. Check that, take the fill plug out. If fluid comes out, note it's color and any grittiness. Looking for a red-brown color. Black indicates it needs a change. If no fluid comes out, drain whatever's in there and refill with plain old mercron ATF.