Looking to replace the 204 frame motor I watched my favorite teach on the subject

and that pointed me to the plate on the motor I have

Reading deeper into this, this is an OLD style of motor frame. 204 Stopped being used in 1953… Of course, mine is a discontinued motor frame…

Looking more at this I see the 203 and the 204 frames are similar it’s the screw mounting width that is different. I think an adapter plate could work. The only dimension that matter is D and U. U is 3/4″ so the center of the motor must be 5″ from the bottom of the plate. Obviously P must be smaller or equal. Watch out for the boxes that stick off the side for the wiring to enter.

LOOKING AT A MODERN NEMA CHART:

All the newer motors have 7/8 shaft meaning the pully will also need to be changed. The 145T looks interesting… Some shopping:

There is hope.

there are charts for the motor mount brackets: