Big block -to- small block "Profiled Adapter Kit" from SMR Transmissions. I was running this adapter to mate my 440 to a 46RH transmission and it worked perfectly. I've since decided to go back to a small block and now no longer need the adapter. It's pretty slick - this is the specific info from SMR's website - adapters:
  • ADAPTER PLATE is CNC PRECISON MACHINED (for exact dowel alignment assuring precise crankshaft to input shaft alignment) 1/4" 6061 T6 AIRCRAFT ALUMINUM which provides a very strong union between the engine and the transmission.
  • CRANKSHAFT ADAPTER is a CNC PRECISION MACHINED steel plate which moves the flexplate rearward 1/4" (the thickness of the adapter plate) to accommodate the use of a standard dimension torque converter and starter to ring gear alignment. This permits the use of the STOCK STARTER* so no special aftermarket starter is required.
New they're $724.50, I paid $700 when I bought it, selling for $600 shipped. Does not include the flex plate. Have to remove the d-side lower engine ear for the starter to clear, as shown in the pics. Any questions just hit me up or e-mail [email protected] - Sam

Gotta have pics :) -