You will need an adaptor to use the 5 speed with the older transfer case. The 4500 came on the later model IFS trucks, with the diff on the driver's side. There is an article about putting the NV4500 in a '71 Suburban with a NP205 case. The adaptor was from Advance Adaptors. There will be some work needed to put the 4x4 stuf under the front of the 2x4 frame.
'79 GMC shortbed 454 th400 14 bolt FF NP205 Dana 60