I wonder when they started using the updated fifth gear nut on these? That would be another thing to keep in mind when looking for an NV4500. It is a realativly cheap part but 270-280ft.lbs. to put the darn thing back on.
The 'stronger' NV-4500's were NV-4500HD. They were used behind the 5.9 diesel and V10 gas. The input shaft size was increased to 1.250" x 10 spline. The output shaft was changed to 29 spline. I use the NV-4500HD on my trucks.
In answer to Alaskan Wheeler's question on the new nut introduction; The following is the complete email I received from New Venture Gear, Sustomer Support on January 2, 2003.
Paul
Cut and paste of email from NVG;
"
_____________________________________________
From: "John Malone" <
[email protected]>
Sent: January 2, 2003
Subject: NV 4500 Manditory Repair
Paul;
The NV 4500 Transmission as used in General Motors, Chevy and Dodge Trucks form its introduction to 1995 suffer a design problem in the 5th gear lock nut retainer. It is probable that during the life of the NV 4500 Transmission, the 5th gear retainer nut will loosen and allow the final 5th Overdrive Gear to fall off the shaft. When this happens SERIOUS damage will happen to the Overdrive. The more miles the transmission has, the more apt the fail to occur.
The update to eliminate this problem is a new 5th gear Nut with a newly designed retainer. The retro fit requires special tools and can not be done properly without the special tools. All Authorized New Venture Transmission stations can make the retro fit. The cost which includes a modification to the output shaft is $250.00, Two Hundred Fifty Dollars.
All transmissions modified by New Venture Transmissions will have the words "NEW NUT" stamped into the case by the top left Overdrive mounting bolt. If these words are not there, consider the transmission as unmodified and a serious threat of failure. Transmissions built after January 1st, 1999 feature a completely new 5th gear retention system eliminating the 5th gear nut problem.
I hope this answers your question on the 5th gear nut failures.
Sincerely
John Malone
NV 4500 Customer Support
New Venture Transmissions
Syracuse, NY"