Same company animated GI Joe and Transformers. If you ever watch the old Spider-man and his Amazing Friends you will hear some of the same music.
nothing new, during the Second Season of both shows, the background music would be used in both shows (except for the instrumental versions of the show themes)
You'll also hear a lot of the same sound effects, and even cooler, most of the voice cast worked on both shows. Try to guess which joes have the same voices as which transformers!
There was a lot of cross-usage, because all of Sunbow's shows drew upon the same sound library. Each show had a few specialised clips though.
I definitely remember musical tracks from both shows being used in each other's shows. One in particular is the G1 track that had tension in which usually the Cons have the upper hand being played in the GI Joe episode, "Operation Mind Menace".