From the picture it looks like your truck is a hydramatic truck. That's one reason the floor pans don't match. I don't understand the 2 piece cover though. I have two '54 GMCs, a 3 speed and a hydramatic and both have a one piece cover.

"It's just a phase. He'll grow out of it." Mama, 1964

1956 Chevy 1/2-ton 3100
1953 Chevy 6100 "The Yard dog"
1954 GMC Suburban Now with a new proud owner.