Better check with these guys; http://groups.yahoo.com/group/39-47Dodge Dodge truck forum for 39-47 models. Also might check with the PilotHouse group at www.p15-d24.com .
What are you looking to do? I have a 39 Plymouth I swapped a 5.2 Mag EFI motor into with very little fabrication. There is actually a guy on ebay who makes a set of Mopar small block universal weld in or bolt in mounts for around a 150.00. Easy swap, fuel efficient motor, very cheap at yards. Just my two cents. Jon