I like your exhaust work! Do you have some more pictures of it?
Also.....FWIW, I had a 63 Dodge M37 Military truck for a number of years. Drove it every day. When I got it, the transfer case was inop, with a huge crack in the case, so I found an NOS one from a guy in North Carolina that's a serious collector. NP200. All gear driven. That truck had a top speed of about 47-48 MPH, but would do it going up a tree. The transfer case was the loudest thing on the truck. Drove it probably over 6 years everywhere and it never gave me an issue. And keep in mind, that truck was a true FULL TIME 4WD. No lockout hubs. So, geared transfer cases WILL make some noise regardless.