When a NEMA motor has special mounting dimensions, flanges, or special shaft features, this is indicated by adding a suffix letter to its frame number.
For example: a 254TS frame motor indicates that the motor has a different shaft extension length and diameter than a 254T frame motor.
The standard suffix letters and their meanings are as follows:
C = C flange mount
D = D flange mount
P/PH = Vertical P or PH flange mount
T = Standard shaft for belt service
TS = Standard short shaft for coupling applications
Y = Special mounting dimensions
Z = Special shaft extension