Gdads, thank you! I'll have to get. Some of that. I Googled previously and it said; "Yes, some WWII military trucks did have interior rearview mirrors, but not all." That, coupled with the fact that it had two perfectly drilled holes and the removal was as difficult (as if it had been on for 80+ years), led me to believe that it was original. It's definitely period and, considering it was used as a farm truck in it's past life, there were no frivolous additions after purchase. All we've found are a few "redneck ingenuity pieces. Haha