Fitting Matchmaker X to SRAM Guide T brakes?
Further research shows there are two systems, Matchmaker and Matchmaker X. My Guide T brakes allow the use of Matchmaker and the new Eagle Shifters use Matchmaker X. It seems as though all of the other Guide brakes (including the R the bottom picture above) use Matchmaker X.
I either need to find a Matchmaker clamp adapter like this https://www.sram.com/en/sram/models/db-acc-mm-a1 (which I'm unable to find in Europe), or swap my brakes at the same time.