Oil pressure extensions

[jk66gt350]

Another post about oil pressure extensions made me think of another question.  I've seen hex shaped oil pressure extensions like the one on my 66 GT 350 made from both steel (most that I've seen) and aluminum.  Are aluminum extensions correct for any 65-70 Shelby or Mustang SB or BB applications, or were the originals all steel, or ?

[TLea]

Aluminum started around May 68 on j code

[jk66gt350]

Thanks for the reply and info.