I think (and I may be wrong) that there is currently a Pacific up for grabs on eBay that might be a "Polydrive" model. I put in a rather low bid (just for kicks), so one of you will no doubt end up with it.
Here's a picture taken from the site of the underside:
Type in "Vintage Brass Toy Train Engine Tender Locomotive NY Central 5314"...and let us know what you think.
Mark (still) in Oregon