At the time, IBM offered the /67 to Universities at a substantial discount (I believe even less than the /65). Thus, several schools bought them with Michigan, CMU, Cornell, and Princeton that I am aware of; but I suspect there were others.
TSS was late, and the first releases could have been more stable. Cornell and Princeton chose to run their systems as /65 using the original IBM OS. CMU and Michigan both received copies of TSS with their systems. Michigan would do a substantial rewrite, which was different enough that became the new system MTS. CMU did a great deal of bug fixing, which went back to IBM, and they chose to run TSS. [I believe that CMU runs OS/360 by data and TSS at night until they felt they could trust it to not crash]. Nominally, TSS and MTS should share programs, and with some work, both could import source programs from OS/360 [My first paid programming job was helping to rewrite York/APL from OS/360 to run on TSS]. So the compilers and many tools for all three were common.
MTS and TSS used the same file system structure, or it was close enough that tools were shared. I don't know if OS/360 could read TSS disk packs - I would have suspected, although the common media of the day was 1/2" mag tape.
This leads to a UNIX legacy that ... Ted's fsck(8) - which purists know as a different name in the first version - was modeled after the disk scavenger program from TSS and MTS. icheck/ncheck et al. seem pretty primitive if you had used to see the other as a system programmer first. Also, a big reason why all the errors were originally in uppercase was the IBM program had done it. In many ways, neither Ted nor I knew any better at the time.
Clem