I believe this is the one that should fit your truck. The larger trucks have a smaller hump. I used this one on my 1979 Chevrolet C70, it was the closest fit I could find.
https://www.classicparts.com/1967-72...ctinfo/39-033/
Link to my C70 showing pictures of the floor mat installed.
http://67-72chevytrucks.com/vboard/a...1&d=1480120684