Trivia Question

I've been neglecting you. I'm sorry. Work's been a bear and all that. But here'a a perhaps marginally entertaining question.

We've all been reading about the Big Three automakers recently. Well, more accurately perhaps, it's the only three nowadays. But once upon a time, many years ago (more than thirty), there was a group sometimes referred to as the Big Five. Here's the question:

Who were the other two? One's pretty easy, the other maybe not so much.