If your running big tires and off road a lot, go to the T 176. If you have close to factory tires and like the 5th gear, stay with the T5 or better still, World Class T5. It has better synchronizers, bearings and hardened gears. It was used behind V8's in the Mustangs. I went with a rebuilt unit for $500 and have been very pleased. I bought the Jeep with 40K on it and the original unit went out at 67K. I now have 150K on the rebuilt one and all is going strong. I don't know how the first owner shifted, but if you can learn to be smooth/gentel, it will help...it did me.
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