Eric, Gene is a member of the STMFC list, he just posted something about an hour before your request. He has the AFE’s for the M&StL and is quite generous is sharing information when he has it. I have copies of just about everything he has prepared on M&StL cars. Clark Probst, also a member of the STMFC list, and has published a number of articles on modeling M&StL rolling stock. If you have further questions about M&StL freight cars, one of us should be able to answer.
Here is some additional information on the 65001s, which I found in some notes from Gene.
USRA hopper cars were used by the M&StL. This group of 178 hoppers, 65001 to 65355, purchased through Hyman-Michaels, first appears in The Official Railway Equipment Register in April 1944. The cars were purchased F.O.B. the Pennsylvania Railroad and Shaffton, Pennsylvania and most of them were put in service at that point. They arrived on the M&StL piecemeal and were put to work immediately.
According to M&StL Records they were built in 1920 and 1921 by the Pressed Steel Car Co. Some cars rode on Andrews trucks, other on National Type B, and still others on Bettendorf trucks. There were still 99 in service 10 years later and one served until 1965. A letter dated January 25, 1954 from J. W. Devins directed that thereafter when cars of this series "become candidates for heavy repairs, they are to be set aside for retirement." M&StL hopper car 65297 can be seen at a coal mine near Rapatee, Illinois in an M&StL promotional film made in 1948. Jay Williams offers a photograph of M&StL 65327.
Hopper 65243 was originally built 6-22, capy 100,000, ld lmt 129,000, lt wt 39500 WMX 11-41, repacked 11-29-41 WMX, length over end sills = 30'-6 3/8". (sketched at C.L. yards M.C.W. 3/9/43)