EBO has always had some odd ideas with balls, sometimes a bit too odd. Oddly enough around here I never saw very many EBOs used, and that is with an Ebonite Center about 45 minutes down the road. The house I primarily bowled in was always heavily Columbia or Brunswick, with Storm a bit more later on.
We had several older people that still bowled with Urethane when I first started in the late 90's and by the time I had to stop almost all of them were throwing one of the Messengers.
I can remember a Red, White and Blue Ebonite ball, seems like a Soccer ball maybe, and there was something clear, oh the Skull Ball, but I'll be damned if I remember who made each one.