not interchangeable - the 55-57 hinges [57 hinge pic] mount to the firewall only - the 58/9 hinges [58 hinge pic] bolt to the firewall and the inner fender as well, and each bolts to the hood differently - PLUS the spring for 57 mounts entirely on the hinge, the 58 spring mounts from the hinge to the inner fender

Bill

Moved over to the Passing Lane

"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir
"When we tug a single thing on an old truck, we find it falls off" ~ me
Some TF series details & TF heater pics