Difference Between USRA Light and Heavy Mountain

[coalsootkid]

A few years back, I picked up a HO scale Bachmann mountain painted for the Southern. Unfortunately, I ruined the shell while trying to remove the paint. I can't seem to find the shell for the Light version but it appears the Heavy version shell is still in stock, would anyone be able to tell me if the shells are interchangable between the models or what version I have?
Thanks

[Tenwheeler01]

Nope.   Light is a plastic shell, Heavy is a metal shell. 

[trainman203]

Why in the world would anyone want to remove that beautiful Southern apple green.