I have a 90 dodge 3/4 ton with 205 transfer case and nv4500 tranny. I need to know if it is possible to swap it for an aluminum housed transfer case.  

Dodge is kinda funny about splines on there 4500 which can be a issue here. While GM has used 32 spline tranny outputs and Tcase inputs since later 80's and on all GM 4500's Dodge has used 23 and 27 spline so you are going to have to match accordingly.