If your shifter handle is straight, you have a T176 and would need to fix it or find another. If you have a curved handle, it could be a T-4 or an SR4 and both will swap out to the T-5 with no additional parts or mods. I would only go with the T-5 IF you axle gearing is correct for the tire size. If you running large tires with factory gears, then the extra stress on the transmission would be too much in the long run. If matched correctly, the T-5 can be a good choice. I have been running them for twenty years in some of my CJs. The 5th gear may or may not be a gas saving deal. Once again, gearing for the tire size. I got better MPH with a 4 speed (1to1 4th) with 272 and stock tires than with a 5 speed pulling too low of rpm for the load in 5th. With lower gears and the right sized tire, the first and second gears are lower and the over drive is just right for the higher interstate speeds.....it needs to match.
1975 CJ-6 304 T15 Dana20 30/44 3.73
1983 CJ-8 258 T5 300 30/44 3.31 Looking for full or half hardtop buy or trade
1986 CJ-7 Laredo 4.6 stroker T5 300 30/44 3.31
1986 TJ-7 Trail Jeep project in the works
2003 Inca Gold TJ Rubicon