Reference to North Wells Truesdell truss
Indianapolis News 6 May 1873
Photo uploaded by Art S.
View this photo at newspapers.library.in.gov
BH Photo #512386
I don't Know. I have found multiple sources but they don't specify location. I also don't trust the sources entirely. I suspect your hunch may be correct.
Might these have been somewhere other than over the navigable Chicago River? Like over a railroad or something? I recorded information from City of Chicago Annual Reports about previous bridges at these locations a while back. While they don't go into a lot of detail, they do provide some info:
Kinzie Street North Branch: The next bridge was built in 1870 by Fox and Howard and was a hand-turned iron/wood combination swing bridge that was 170 feet long and 31.5 feet wide. This conflicts with the idea that a Truesdell truss was lost in the fire of 1871.
Wells Street Main Branch: A Chicago Annual Report of the Department of Public Works states that the bridge was rebuilt in wood by a contractor named "Harper" in 1856. The bridge was again listed as rebuilt in 1862, this time with Fox and Howard listed as contractors. This bridge burned in the infamous 1871 fire. For this bridge, the dates seems to match. The only catch is that it was built by Fox and Howard. I don't have a photo of this bridge, but other Fox and Howard bridges were combination wood/iron swing bridges like this. Not sure if they also built Truesdell swing bridges, if such a thing ever existed that would be interesting to see a photo of. Here is a regular Fox and Howard swing (Webster Avenue): https://historicbridges.org/illinois/webster/previous_large....
I'm putting this here although I'm not confident of its location. Truesdell apparently built a bridge on North Wells, which was destroyed in the 1871 fire, and on Kinzie St.
So far the info is sketchy.