From previous discussions I think it's just the camshaft? But 5HP seems too little for the difference in cam specs?

There's a similar situation among C bodies with 440's, there's the standard 350HP, the 360HP police package and the 375HP version. The 360HP would be similar to the the 383 330HP? So the small cam costs the 383 5HP vs the 440 at 15 HP? shruggy

'68 Fury Convertible
'69 300 Convertible
'15 Durango 5.7 Hemi
'16 300 S Hemi