I went through a real PITA time of getting a new motor for my 84 TD.

I don't know when the split happened of the top of my head, but the older motor has a more enclosed casing on it. You can't work on the brushes for this model. The newer (83-85?) has the accessible brushes. The older model has a larger circumference and does not fit the black plastic base.

The 126 blower motor is about 1/4" longer than the late model 123... Don't ask me how I know. But I have a brand new 126 motor for sale if anyone needs one. They look identical to the late model 123, but no dice on fitment.

__________________
'85 300TD "Puff The Magic Wagon" - Rolling Resto
'19 Mazda CX-9 Signature - Wife's sled
'21 Morgan 3-Wheeler P101 Edition
'95 E300d - SOLD
'84 300TD "Brown Betty" - Miss this one
'81 240D "China Baby" - Farm grocery getter