The Mount Clemens subdivision local that originated at East Yard operated as 600/601 in the 1970's. Don't know if they used the same symbol earlier on or not. It operated for many years all the way to Port Huron, and was ultimately truncated to Richmond. For a time, there was also a 400 series train that ran from Port Huron to Pontiac (1970's/80's). Was either 450/451 or 452/453 - have to dig up my timetables. Not at all familiar with that City Yard piggyback train. I'd be interested to learn more about it.

Anyway, thanks R Bedell and Stinger for your responses here - very interesting and informative stuff!

RandallG