SBC 400 block build date
Got a SBC 400 "509" and been trying to ID it. As far as I can tell its possibly made in Saginaw due to a casting clock on it. My friend said its an early 70's cheater block probably from a truck, and probably high nickel content. I found the following mark "H/17" which I think is the manufacture date. If it is, then the block would be from 1 Aug 1977. 2 bolt.
Two questions: how does one figure out if it is a high nickel content block and can anyone verify or ID the "H/17" mark?
tks in advance