I imagine if you've been searching for a "Flame arrestor for Citation Excella 1989 RV
you haven't found much. You mention a "454 big block," which suggests a GM or Workhorse chassis. Have you looked for a flame arrestor for a 454 Chevy? Or perhaps just an air cleaner for the same? Flame arrestors are more often used on marine engines, most trucks and cars call them air cleaners except for racing applications.