Flat base, cast engine frame and probably a brass flywheel ... Nice!
SE-2 though isn't it ... as it has the exhaust throttle?
Se1 from looking up the TSB Daniel (that's what I used to ID).
Yep brass flywheel.
It is a ‘48 SE1, and the only time a regulator was used on an SE1. SE2 in ‘48 had a longer boiler with a whistle.
Is that my old engine Jim?