I have heard that theres a pin in the FMX that can get worn down and cause the tranny to slip from park into reverse while running. I would be extremely careful if i were you, until you get it looked at or rebuilt.
I just bought a 69 Mustang recently,and it needs work.One question I have is
> when I put it in park,if its on a gradient,it rolls,or on the level it can
> be pushed,with no resistance.. I do have the parking foot brake,but that
> needs fixing so it dosent work at the moment.
> I think my gearbox is an FMX auto,but should it stay still in park,or is it
> normal to roll(hence the parking foot brake) I'm kinda new to this ,so it
> may sound like a dumb question
>
> Thanks
> Andrew