It has never been completely clear to me whether Model Train Sales Inc. was done solely by Bob Geller, by Chicago Line, or by a partnership between the two.
I think the line was made by Bob Geller, with some parts provided by Chicago Line.
All of the MTSI trains with which I am familar are based on flatcars with various loads. The flatcars look to be almost identical to a Lionel 6424 flatcar, but are marked "MTSI" on the bottom.
There was an assortment of military loads, such as helicopters and planes. There were also boats. One neat car has two spools carrying satelites. I thnk the spools were cut down for this car, I am not certain.
Some of the loads were molded in new colors, and/or with new decorations
I have seen helicopters, planes, and submarines decorated for "Coast Guard". I think they look sharp.
I think they also made miscellanous cars with various decorations.
At one point, Chicago Line went by the name "Parts for Collectors".
Chicago Line reproduced the #35 lamp post, with pigtails instead of a terminal board, before MTH did. They made them in assorted colors. My favorites were black and green.
Bob Geller was making reproduction tender shells at one time.
Here is his web site:
http://www.gellertoytrains.com/