I lost fifth gear in my '98 Cummins. I bought the nut kit that has the two small setscrews and the brass pucks. No instructions. I guess the brass pucks go in the holes first but is there a torque on the setscrews? I also bought the retainer that has the four "fingers" that fit into the nut. Anyone have any experience with this piece?

No experience rebuilding but I went through 7 of those damn transmissions because of that nut! The last 3 had the fix to keep it from backing out, didn't freakin' work!

Is there anything on youtube?

I don't have any experience with those kits, but I do know it is really only a problem with the Cummins trucks, gas trucks don't do it. Must be something about the harmonics in the Cummins that knocks the nut loose.

Torque King has instructual videos on you tube.

You bought a kit and they did not show instructions? Send it back. Just google the 5th gear nut. That fix is garbage.

You need the special nut wrench to properly torque the nut. https://torqueking.com/nv4500-5th-gear-failures-and-solutions/

I bought both special tools, the spanner for the nut and the splined holder for the shaft. The reason I asked the question on this forum is that typically people who respond are more responsible when repairing equipment. What I saw on line were people using the wrong sealant on the transmission extension housing and tightening the gear nut with a hammer and chisel. So people who went on and on about their 3rd, 4th, 5th failure....I don't know if they knew what they were doing or they were just following the YouTube "mechanics".

Clean it well, red loctite, new nut and this lock ring.Lock

I have that lock ring as well. As to the Loctite, I'm looking at 648 for the splines on the gear and 263 for the nut.

Give Dan Brewer a call and he can tell you how to fix it!

Well, put 5th gear together last night. After more than one email with the Loctite tech line, settled on 648 for the gear and 277 for the nut. Initially torqued it to 250 lb-ft (that's all the torque wrench I have) as the factory specification is 250-300 ft-lbs. I then used a breaker bar and a cheater and torqued the living bejesus out of the nut. So I have a new gear, new nut with the two set screws, and the pronged retainer. We'll see how this works out.

and as a very last resort, break out the welder for two big tacks.
hackery at it's finest !

I’ve seen that broken…..