Well, for one thing, this is all taking place on the "ECTA Rules Question" site.
But for SCTA, if you're talking Vintage Coupe classes, they require bodies pre-1949.
And then there are rules for Vintage Engines that can sometimes be up to 1959.
I can't find any Vintage rules that preclude 1948 components from the rules that have a 1948 cut-off.
One must be careful of opinions and falsifications caused by someone adding, subtracting or modifying the actual rules in the book.