Okay, 2 things I see.
One is yeah, someone cut the jimmy part off so they could change to a chevy grill. Do you have a grill? Is it the chevy or the gmc grill? Check this thread, especially post #5, it talks about changing the gmc to a chevy support by removing the parts your's is missing.
http://67-72chevytrucks.com/vboard/s...d.php?t=143068
Second, the fenders are 69-72 chevy fenders, not GMC fenders. You do have the 69-72 gmc hood latch assembly. Not sure about the center grill support.
Maybe you should just run a 69-72 chevy grill...
Good luck, Rg