Radiator support opening for 22" or 26" is a small clue to some point depending upon rear original axle ratio sometimes. Also if it has a power brake booster it will be off-set up and to the driver's side if it was a Hemi for the large Hemi valve covers. Not sure if all Hemi's got power brakes (booster)???

Torsion bars (end coding) were different for a Hemi if I'm not mistaken?