There have been many discussions on interior wwii aircraft colors. This is a very dynamic subject. One article that I have found helpful is by Martin Waligorski who was the editor of IPMSStockholm.org. You may find this informative!
www.ipmsstockholm.org/.../stuff_eng_interior_colours_us.htm
I pulled several kits out of my stash to see what their call outs were:
Revell P-51B Cockpit chromate green
Revell P-51D Cockpit chromate green
AM P-51 Cockpit zinc chromate with olive drab side consoles
Wheel wells and doors zinc chromate
AM P-51C Cockpit interior green with olive drab side consoles
Wheel wells and doors aluminum
Tamiya P-51D Cockpit XF3&5 (chromate green)
Wheel wells chromate green and doors aluminum
If Bronto or anyone has any evidence of aluminum gear bays on P-51B 43-12102, I would sure like to see it. I agree, they probably are aluminum; I would just appreciate a reference!
On the Bench:
Revell 1/96 USS Constitution - rigging
Revell 1/48 B-1B Lancer Prep and research
Trumpeter 1/350 USS Hornet CV-8 Prep and research