It's the belt the runs and turns all of the necessary engine components like the alternator, AC compressor, engine fan, waterpump, crankshaft, and others as well.
It's the same kind of belt as in...
you will need to swap the output shaft and tail housing from the old 4x4 transmission to the 2wd tranny which requires complete disassemble and then reassemble of the transmission
I found this picture when I was having problems getting my fan belt back on my dodge. I have an '04 Dodge Ram 1500. It worked, after fighting with it for over an hour I found this picture and had it...