Don't know if you got this sorted out or not, but these motors are available all over the place, you can buy them new on E bay, or usually quite a few for sale on the C body site, FCBO. As a C member also, I know there are a lot more C bodies that got power windows, so lots around. You will need the power window motor that is odd numbered for drivers side, or even numbered for the passenger side. Just about any year will work, though you might have to change the lower mounting bracket and replace with your own bracket off of your motor. Or, go on E bay, and order the rebuild kit for your motor if it is running nicely. The kit is cheap, and you can re and re the gear, the pucks etc in about 1/2 hour.
However, once you have the motor out, I would suggest taking the body off and cleaning up the armature etc, remove all the black and grey old grease, re lubricate everything and test it while you have it out. Just hook up 12 V to the green and purple wires then reverse those connections to go the other way. Last thing you want to do is re install and find you have done something incorrectly! Put "power window motor" in the search engine on FCBO and will find complete videos and detailed instructions on all of this stuff. Worth it. C Shaft