I have a 1968 Firebird 400 with an automatic transmission that just went out. I was going about 40, and all of a sudden it made a noise and wouldn't go any faster than 20, though the engine was racing like it was going much faster. Reminded me of when someone accidentally shifts into neutral, and the engine revs up, but it's not going very fast. Does anybody know what the cost is going to be to repair/rebuild it?