Picture one two and three look mid to late 70s maybe later ? Picture four has the early bracket but is missing two brackets and has a later pump and pulley. Your two pulleys if you can read a GM part number on them I can ID them for you.
Heres another thread on 6 cylinder brackets. For our generation of trucks 63-66 the 230, 250 and 292 uses the same brackets but different pulleys.
http://67-72chevytrucks.com/vboard/s...d.php?t=605396