S standard questions

[D standard]

Just dug into my "S" to get started on it this winter. I knew the casting was broken were the seat mounts, and the flanges under the battery tray (was used to skid trees for 20 years and a few fell on it obviously). I learned that the engine is a 51 SE power unit, that was a surprise not a 49 as the dash tag stated. So in most models the power units had higher output than the tractor models, is this true on these? Would this have aluminum or cast pistons?
Dash is 5325061 S, engine flange and valve cover tag 5523004 SE.

 

[D Case Guy]

The higher output on the power units was likely a result of higher rpms, and not any internal differences that would increase the torque level. I believe that a 51 would still have cast pistons, but they could easily have been replaced with aluminum ones at some point.