5 gear loss

my 97 dodge 5 speed is now a four speed, there was trouble with the 5 gear on this trans wasnt there ? can a newer 6 speed bolt up to this truck? or is it a hard fix?

remove the tail housing,you will see a nut that has came loose on the output shaft that keeps it from engaging 5th gear,mopar and aftermarket make a replacement nut,it has to be tighter than the hubs of hell to not get loose again
i presume its a cummins?,if so aftermarket has a better solution than mopar,my buddy got his from a place in denver,google 5th gear to find it

yes its a 5.9 thanks is there room to put 2 nuts on?

If it is a NV4500 trans, there are youtube videos on the fix.

If it is a NV3500, then ?

I went through 7, YES 7, NV4500's in my 1999 Cummins diesel dually. Each time the nut came off I was hauling a 48" enclosed loaded and the damage was much more than just the nut coming off! The last two trans had the aftermarket fix, didn't due any good. I will NEVER buy another NV4500, or G56 trans again in my life! I haven't tried to ruin an NV5600 yet, but probably will sometime in my life...

the fix we used from denver looked bulletproff to me,it had fingers that fit over the nut to keep it from turning and a splined center that kept it from turning,plus it was just long anough that it couldnt slide back on the splines as there was a stop behind it that i think but cant remember for sure was the inside of the tailhousing,use a mopar nut and tighten just past the hubs of hell tight

Size matters....lol