Need info on 3RD Rail MP54’s

I’m looking at a couple of 3RD Rail MP54’s #619 and 639 both powered. Anyone have these or know what the specs are.  I e-mailed Scott today and am hoping to get a response.  Also the #639 is going for a lot more at this point than the #619.  Anyone know why since they are both new in the OB.

Any help appreciated.