Originally Posted by Hydro Junkie

Actually, only the P-51, P-51A and A-36 had a lower service ceiling due the the use of the 1710 Allison engine. The D, H and K had handling issues when the the rear in-fuse tank was full, mandating that tank being used first, even before the drop tanks, to restore the handling to what was normal for the "razorback" Mustangs.