Good you mentioned Mueller Electric, I just noticed they offer
alligator test lead sets such as BU-00285 18". Not sure what clips they are using, I thought they're different from their main lineup of clips.
BU-30 alligator clips I dislike, jaw too small only 2 teeth on the side, and it's overall too short and the boots are shaped wrong, like 1970's disco jeans. They've been around since
1940! and great for tube amplifiers but things are a bit more refined 81 years later. I have lots of them and the build quality is good. The 70 series clip ad 1957 is funny, spring goes 60MPH !
Starting the DeLorean and going back to Radio Shack, the superior alligator test leads are made by
Tokyo Teishin Electric (T.SIN) they have a longer jaw 5 teeth, tight crimp connection, boots that are better shaped, ~20". I think they (medium size) are TLA-2 or TLA-82.
Test Lead Catalogue including some metrology-grade on their website but alas no sign of distributors outside of Japan.