518 and a 360 (408 Blueprint engines stroker)

Professor Fate said
The A518 (46RH) is a 727 derivative, and should use B&M 10236, if I am not mistaken. The B&M 10239 is for A904 and A500 (42RH).
@Johnny Mac should clear it up for you.

Sorry typo, yes I do have the 10236 flex plate. Thank you.