Id num for trucks is on panel in eng compartment.
ca41 r180 4.11, ca43 4.375 ca46 4.625 look for 720s 80-83
86+ hardbodies and 720s (4.11 or 4.625) also some of the frontiers had ca45 (4.54) 2003+ , started changing to r200s mid 80s so look for 4 bagers, and yes will be on 4x4 front diff only. The 4.44 can be found on some of the subies (dont know which)
I got this off the nissan-infiniti forum dont remember where old post.