Correct 1965 Small Block Fan Clutch Bolts Head Mark?

[James W.]

I am trying to determine what the correct head mark is for the fan clutch bolts, specifically for a small block car. The current 1965 TIMJG says that they are a cad plated, grade 8 bolt with a split lock washer, but give no reference to the head mark. I did a quick search and found a post saying that '66 fan clutch bolts have a head mark with a single "S" on the head. The current repro bolts that ZIP sells is a grade 8 designation with "WB" on the head. I have also seen the the a grade 8 bolt with an "L8" on the head. Are either of these correct or is the "S" designation correct.

Thanks,

James

[Michael M.]

I am sure "WB" and "L8" are known head marks. The head mark on my car is "RBW" in the picture with the mirror. The other picture is also a known head mark "SBC".