Dan the Gear Man® Tech Note 1:
With the original Getrag G360, the Splined Coupler is not bathed in oil, so spline wear due to direct metal to metal contact is very common. If your coupler splines are worn, there is a good chance the matching shaft spline is also worn. Installing a new Coupler on a worn shaft will only be a short-term fix as the worn shaft splines will quickly wreck the coupler splines.
Dan the Gear Man® Tech Note 2:
Grease the shaft and coupler splines on your new coupler before installation in a truck with the original G360 5 speed manual transmission.
Dan the Gear Man® Tech Note 3:
If you are adapting a 29 spline output Dodge NV4500 or NV5600 to use with a 29 spline NP205, you need to have the 4-1/2" wide cast iron factory round 6 bolt x Hourglass 8 bolt transfer case adapter. You also need to remove the transmission output seal and add an extra quart or so of oil to the transmission to fill the adapter space. Install a new TK10517 Double Lip, Double Spring Transfer Case Input Seal in the back of the factory adapter along with new TK10519 and TK10529 Gaskets. TK10517 Seals oil both ways so it acts as both the transmission output seal and transfer case input seal. You must also apply threadlocker to 8 bolts that attach the adapter to the transfer case.