The firewall is pretty much the only place I've ever seen them moved to. Leaving it under the floor isn't all that bad. The truck can be charged and jump started from the stud on the starter without having to mess with the battery under the floor.

I'd leave it alone.

1950 Chevrolet 3100 (Ol' Roy)

1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)