Tim is right on the panel attachment difference. The access cover difference is the earlier doors have nutplates and the '54 doors use sheet metal screws. No one will notice.

"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.