D-5, D-10 and D-20 are the same performance-wise, the latter two are more laterally stable because of the fin which in War Thunder RB means nothing. Im not sure if it's even modeled in game. The D-30, however, is MUCH more powerful, running on postwar boost settings (F-51Ds were deployed to Korea with higher boost, the D-30 is one of those, hence the radar antennas all over it) and is the P-51D you want to fly. The extremely minor IRL differences in blocks after D-5: P-51D-10NA and P-51D-5NT: Added elevator bob weights. These helped offset the rear CG problem with the aft fuselage fuel tank by acting to pull down on the elevator cables in a tight high-G turn. P-51D-10NA: Added dorsal fin and reverse boost tab. P-51D-15NA: Standardized landing gear warning lights. P-51D-10NA: Replaced mechanical oil temp gauge with an electric one. P-51D-5NA, P-51D-5NT: Moved supercharger aneroid switch from firewall to cowling former. P-51D-15NA, P-51K-10NT, and P-51D-25NT: Replaced direct reading fuel pressure gauge with a pressure transmitter. P-51D-10NA and P-51K-5NT: Two speed booster pump switch replaced with single low speed switch. P-51D-20NA, P-51K-15NT, and P-51D-25NT: Electric PRIMER pump replaced the manual one. P-51D-20NA #401, P-51D-25NA, P-51K-10NT, P-51D-20NT: Replaced fabric covered elevator with a metal covered one and changed the angle of the tail incidence. All blocks after D-20 came from the factory with the K-14 gyroscopic computer gunsight, which to my knowledge was field issued to Mustang units and installed in the field in the older planes. Not sure though. This means ingame the D-5 and D-10 should have a non-gyro sight, and according to my sources came from the factory with the N-9 sight with circle reticle, the same one as the P-63s.