the openings are the same but the 55-6 grill mounts inside the opening, the 57 grill laps on top of the opening surrounding ridge, the difference is there's holes on the face of the opening for 57, with a 'dimple' flat area around them .... if you put a 56 grill in a 57 you'll have to fill the holes, if a 57 grill in a 56, you'll have to make the holes .... note the holes each side of the 56 grill in a 57 truck - the 57 grill back in

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