[Jeff Lee]

There used to be a section in the rule book that said something like..."can not replace parts with lighter versions of parts unless specifically stated"...or words to that effect. I no longer see that but I believe that is the tradition that NHRA follows.
I'm with Mark, a specific rule and possible interpretation to every nut and bolt on a Stocker would take volumes to address.

I once challenged that since the OEM has roller rockers (like an LT4 as an example) that they should be allowed on a 327. Apparently NHRA doesn't see it that way.

And Ken, just because you can't find a performance advantage to running an aluminum center section in Stock doesn't mean it can't be done. The fact I have no experience in this (in Stock) has no bearing. When I raced S/ST I took advantage of putting an aluminum 9" in that car. And my present car has gun-drilled axles, back-cut gears and scalloped spool. So I do put my money on the fact there are improvements.