Engine Question

RB stands for Raised Block. All 413, 426, 440 wedge motors are RB's including your 440 Magnum.

FWIW, The 361, 383 and 400 are B blocks. The difference between B and RB blocks is the distance from the centerline of the crank shaft to the deck surface the heads bolt to with the RB being larger therfore the "Raised" designation.