Luftwaffe and Allied Air Forces Discussion Forum

I am trying to distinguish between the D-model Razorbacks - exterior differences only. I've found the following notes about them and wondered if I haven't missed anything. If there are any Thunderbolt buffs here, your input would be very much appreciated

D-RA was alike the C-2
D-1-RE onwards had additional cooling flaps compared to C
D-2-RE onwards had the turbosupercharger shroud removed (does anybody have a picture of this?)
D-5-RE onwards had belly droptank/bomb provision
D-10-RE had a new engine, but I don't think there were any external differences otherwise (+ "hydraulic flap equalizer deleted" - is this visible on the outside?)
D-15 onwards had underwing pylons, a jettisonable canopy (which I assumed looked the same?) and redesigned cooling flaps
D-20 onwards had longer tailwheel strut, redegined underwing pylons (what was the difference?) and discarded camouflage from 42-25274 onwards
D-22-RE had Hamilton Standard Hydramatic 24E50-65 13'1 7/8" propeller in place of the Curtiss Electric 12'2" as earlier used (+ more changes, but I don't think they'd be visible on the outside?).
D-23-RA was like D-22-RE but with Curtiss Electric C542S 13' propeller

Many thanks for any input!