Hblair, the F6F has better jabo capabilities as the F4U-D (beats it by carrying 2 more rockets hehe). Should have the same perk cost as the hog-D.
I would also let each side have its own vehicles. With the M3 and LVT's being the only ones the 2 sides share.
The Allies have the faster moving M8, the M16 and the M3. Axis would have the M3, Flakpanzer and the PanzerIV. Allies have better ground attack planes so that should balance that out as far as the ground units is concerned. Besides, Shermans really couldnt go head to head with german tanks, they would generally call in air support to take them out or overwhelm them with sheer numbers.