I have a 99 Dodge Cummins Standard PU 4WD with the NV4500 (manual) tranny and lost 5th gear. Runs great in R and 1st thru 4th. WTF. I have heard the lock nut has backed off and have received all kinds of fixes. The new replacement kit for $60. Put this on with Loctite and torque to 300ftlbs and set the set scews. Made 281,000 miles on the tranny until this with just replacing fluid at 200,000 miles. Any thoughts?