98 12V, 5spd 4wd long chassis cab, 5th gear spun, NV5600 time, need help, links, etc.

[GM Guy]

Hey guys,

My boss spun 5th gear off for the third time, and he is going to NV5600 swap it in the future, but will still be fixing the 4500, but for the last time. He would like to have the 5600 swap at the ready before the upcoming 4th and final failure. He knows as much as I do concerning this, so he asked me to look into the swap.

so I ask you guys, what are the keys to a sucessful NV5600 swap? any years that the trans needs to come from? any different t-case mounting any different t-cases behind the 6 speed? any different flywheels?

with no knowledge base, I estimate the easiest would be to get the 6 speed and t-case out of a junker 99-02. reason being i would think that trans. crossmembers, bellhousing contours, etc would all be for the same body style.

am I correct in thinking this?

any input greatly appreciated, thank you!

 

[THEFERMANATOR]

01-02 is what you are after for a 6 speed. I know they say they built em, but I have NEVER seen one in anything older than an 01. And yes get the transfer case as there could be 2 different input shafts in the one behind a NV4500 depending upon year. And have you used the MOPAR upgrade parts to repair the 5th gear problem yet? I know many just go in and put the old 5th gear back on and put the old nut back on and try and peen the threads to lock it in place. And this doesn't work. If the 5th gear is even sremotely loose on the shaft it will come off again no matter what you do. And I never had one come off when I put in the new style split nut with the red loctite.

 

[GM Guy]

idk about using a new gear, but i know he has used the most recent nut.

the thing has a fuel plate, and pulls goosenecks loaded with tractors. only uses 5th when empty though..but it is a tandem dually 32' PJ with a dovetail. this is the main reason for his failures.

 

[GM Guy]

if anyone sees a rolled 01 or 02 chassis cab long wheel base with cummins 6 speed 4wd for sale, let me know. the tranny came apart this last go around (input or output shaft snapped), and if a 6 speed came up, it would be a nice upgrade. otherwise, it is big buck time for a full on rebuild.