[mgarblik]

Originally Posted by 73T/A

I mentioned the 3/8 rocker studs and such that were on the heads.In retrospect the 3/8 rocker studs aren’t much of a indicator in how the heads were used in the past do to the fact that they can be changed and swapped out with 7/16 versions in minutes.Do to the fact the heads were 31 years old when I acquired them it’s anybody’s guess.

You mentioned that the 197 heads with a date code of Dec 1970/Jan 1971 would not be used for testing etc due to lead time for the 1973 SD-455 head.It seams plausible to me that there would be enough time .Not necessarily my heads but heads with that date code in general.I never heard that the SD-455 program was turned over to production in the Dec 1970/Jan 1971 time frame.Are you referring to casting the cylinder heads.I have seen a SD-455 head dates of Oct 1972 and some with no dates stamped on them those are probably earlier yet.Im sure the SD-455 guys know.

You are so right about some of the mysteries that surround these engines. My early 73 SD-455 engine has NO casting numbers on the exhaust ports and NO date codes. Only the full part number on each head. It has "A" connecting rods in it so I feel safe saying it was a pretty early engine.