Actually the pump rod is the same length for both B and RB engine families. Hughes Engines offers only 1 hardened fuel pump rod for big block Chrysler engines. So either the shop put in a defective rod or your cam ate it up fast and deposited the shavings into your nice, new engine. If you still have the old, ate up pump rod take a close look at the ends. What you see may surprise you. Have you checked to see if there are any shavings in your used filters? Even if there are none I still say its a very wise investment to get a magnetic drain plug. It will pick up any loose metallic particles in the oil and that is a good thing!