That looks A LOT like the bumper off my 1966 chevy biscayne and I'm almost sure it is in fact a gm bumper
If you go on E-Bay there is a 1965 Chev Impala for sale. It is definitely the bumper. The 1966 was close, but not the same.
Well one good thing is that it is worth more as an Impala bumper then a Maverick bumper. Throw it up on Ebay and get some Maverick money.