If you have a NV4500, I suggest too that you rebuild it. Make sure you have the following upgrades done...
1. Later half (95-up) shift tower. The square top fixes all the shifting problems associated with the earlier bottle top version. Early model bottle tops are notorious for 2-3 gear popping out.
2. Later half (95-up) synchro's. These too are updated and much stronger.
3. Synchronize the reverse gear. Early models do not have such animal.
4. 5th gear nut upgrade.
Also, the GM version does NOT have a rear output seal. The adapter will fill completely with gear oil and will be against the t-case. Make very sure you have an excellent seal between the adapter and t-case. If you don't, when the engine is started and the tranny internals start turning, it creates pressure and will force the oil through any thin/missed spots.
Ask me how I know this..... 2finger
Short shifter is available but it's for the Dodge NV4500's only. Theoretically you could use it in the GM, but you would have to get a Dodge shifter handle because the thread size and pitch are different than Chevy's.
Think about adding tranny coolers. They would replace the PTO covers and will aid in keeping temperatures down. They have provisions for a temperature guage, which I added to mine. The ones I used are from Blumenthal and are available on the web.
I also highly recommend from
www.quad4x4.com, their oil filter kit. It has a beefy filtration system and a big magnet inside to catch any metal shavings. Yes, the tranny already has a magnet on the bottom, but an extra one won't hurt. You can use it with out without a tranny cooler.
You will also need to remove your center hump, weld closed the SM465 opening and cut a new opening for the NV4500 shifter. The SM465's is forward on the top, whereas the NV4500 is rearwards.
If you have an NP208 you will have to modify the shifter housing as that and the shifter boot cannot share the same space. No mod is required for a NP205 as the hole is fine for that shifter.
That's all I can think of right now.
Manny