To make things more confusing, I emailed Mike about getting a 1950/8 and he said it may be awhile, and that he was going with Neu motors now. More efficient and cheaper than the Lehner he thinks. It's a 4 pole design and looks to have an open endbell from what I've seen, but there sure are a lot of choices in that brand, that's for sure. I dunno which one would match to a 1950/8 though, Mike never got back to me on that one.
http://www.fastelectrics.com/blmotors.asp
I'm thinking a 1515/2.5D or 1515/1Y? Looks like they are available with cooling fins, too. I'd buy it from Mike of course, just sharing the motors I've found so far.