Didn't MTH take over the Madison car tooling from Williams while it was being made at Samhongsa? (sic?) They came in those "Custom Trains" or something boxes.
That's where he got the Weaver E8 tooling with the big "eyebrows" over the windows too IIRC.
I don't think that is the case since Williams by Bachmann has offered many of the same heavyweight cars Williams did originally.