Attention: TDR Forum Junkies 
I had the 5th gear nut fixed at a local shop, I provided the parts from Standard Trans, upgraded nut, gallon of Syntorque and special tool from SPX/Miller. Was going to do myself, but glad I didn't attempt it in the driveway.
Observations:
1) I had been driving truck for a few weeks after nut falling off. With nut and gear floating around for a while, it messed up the threads on the shaft a little bit. They had to chase them to get back to normal.
2) Transmission mount was broken. One side was totally separated. This is a great time to replace it.
3) Oil was likely original, 168k miles now. Was contaminated, but not terrible. Running with gear and nut loose probably didn't help.
I feel pretty confident that it will hold. Gear fit was good, threads were chased, cleaned, loctited. Nut torqued to 275. Brass plugs jammed in by set screws. Concave washer putting pressure on gear. Shoulder of nut staked onto shaft. The upgraded nut is definitely and improvement over the old one.
Only time will tell...
Observations:
1) I had been driving truck for a few weeks after nut falling off. With nut and gear floating around for a while, it messed up the threads on the shaft a little bit. They had to chase them to get back to normal.
2) Transmission mount was broken. One side was totally separated. This is a great time to replace it.
3) Oil was likely original, 168k miles now. Was contaminated, but not terrible. Running with gear and nut loose probably didn't help.
I feel pretty confident that it will hold. Gear fit was good, threads were chased, cleaned, loctited. Nut torqued to 275. Brass plugs jammed in by set screws. Concave washer putting pressure on gear. Shoulder of nut staked onto shaft. The upgraded nut is definitely and improvement over the old one.
Only time will tell...
Somebody knock on wood ..... If it goes again or when my clutch goes ,I will go back up with the fully splined mainshaft. Its just not a job you want to repeat... ... ...
