What will happen?
I recently bought a 5150 but I don't have a cab yet so my dad's friend is letting me use his.
But I'm almost positive it's a bass cab, it's an Ampeg Classic.
you'll loose some of the high end sparkle and gain a bunch of low end. as long as the ohm ratings match nothing bad will come of it.
i used to be a mod, then i took an arrow in the knee.