I have a 1969 C-20 with a stock 350 and it does have HEI. I am replacing the spark plugs and plug wires with some MSD #31239 cut to fit wires.
The plugs I purchased at O'Reilly's are R43, the ones I removed are R43S.
Is that going to make a difference? The only difference I see is that the R43S is a little longer and extends farther into the combustion chamber. What would be the advantage of a longer plug?
The plugs I removed look fine, no oil build up or anything out of the ordinary so I don't think a hotter plug would be necessary...?
The AC Delco website even says the R43 plugs are the correct ones.
http://parts-catalog.acdelco.com/cat...log_search.php