The late (8E series) had the firewall mounted MC.  Early Champs used NAPA # 2796  8Es used # 36072

(Regarding changing truck brakes to v8 car brakes)
  Without the 8E backing plates, you'll not be swapping any Lark brakes onto
that Champ. Not unless you know something I don't.  While it's been said
that the late Champs went to the "car" brakes, in essence what really
happened was they upgraded the Champ brakes to use the self-energizing
innards of the car brakes. They had to make a new backing plate to
accomodate said change. Read that: the Lark backing plates won't work on the
truck. The Champ still retained basically the same drum that 1/2tons had
used for some time. Remember too that the trucks had 11" brakes - front and
rear.
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I dont why the Ch*bby drums wouldnt work on the rear. The 1/2 ton Stude 
OEM drums are the same on all four corners.