You can go back through the amsat-bb archives
It is possible to search the AMSAT-BB archives by using the "site:" command in Google.
For example, to find all mentions of the word "G5500" in amsat-BB, type this line into Google: G5500 site:http://amsat.org/pipermail/amsat-bb
To restrict the search to a particular year, type: G5500 site:http://amsat.org/pipermail/amsat-bb/2020
Perhaps you'll find the 5500 rotator threads quicker with this search technique. Just fine tune your search in that 'keyword' before the 'site:' to zero in on your particular