I am putting a one-ton bed on my project and need to order a new front panel from American classic. The on-line catalog lists two sm147 for early 1951 back and sm236 for late 51 forward. Both parts seem to have the exact same picture in the catalog. I don't know what year mine is. Can someone tell me what the physical difference is between these two front panels?

1953 Chevrolet 3600
Fried Green T'mater (Vern)
In the Stovebolt Gallery
Caution: Political Statement
Man who runs in front of car gets tired, man who runs behind car gets exhausted.