Re: Mechanical difference between K-37 and K-36 question

general rule of thumb for telling if an engine is soak or super heat is to look at the general , external arrangement of the front end.

Smokebox:

On a superheated engine, there is usually a cluster of 4 or 5 bolt heads on each side of the smokebox just forward of the end of the jacketing. These are for the mounting brackets inside which hold the header unit of the superheater. This was a common visible clue on Baldwin & Lima engines and I believe ALCO too.

Cylinders & Saddle:

Superheated locomotives usually used Piston Valves and the steam delivery pipe exited the smokebox from the side at or above the centerline and attatched to the piston valve housing just off center of its top.

There are some exceptions to these rules and generally are due to in shop modifications