Local shop pointed me to Sierra 18-7350 as an alternate part to 388685 which is the specified fuel pump on this site for the QD-21. Looking at the Sierra catalog, it appears that this is the only "square" pump available. My question is, does this also cross to other small Evinrude/Johnson pumps such as the pump# 388833? If so, does this pump replace any small Johnson/Evinrude pump of the same shape?