Here is the link, you may be able to pick out the motor closest to yours, they look like 3500 maybe, if you click on the 3500 motors it should give you a PDF to download info to compare physical size which should at least give you a ball-park rating.
http://www.torquesystems.com/product_family_brush.html
I will see what I have on the encoders, How amny wires to the the encoder?
Al