I used a 2005 5.3 4l60e with a NP241C from a 1991 Jimmy. The NP241C came off a 700r4 that is the same length as the 4l60e, so it bolted up like factory and the front driveshaft is the correct length.
I googled the casting number 473483, it's a 1975-79 250ci.
I don't know much about 6 cyl engines. My main interest is the 4cyl Chevrolet's from 1914 to 1928.