Looks like it was offered in the mid 90s I have a gap in my Mopar Performance Catalogs and cannot find the part number. However I did find an reference in a Mopar Engines Manual from the early 90s:
Machined from 4340 steel forgings, widely regarded as the strongest crankshaft material available, for maximum strength in race applications. Eight bolt flange. Full radius design.
P4529532 "B" engine race crankshaft - 4.15 stroke, 2.625 main journal diameter.
If it not a rust log could be very nice crank.
Bill