Not an A-body, but close enough:
my '93 Dakota (5.2, automatic that's been replaced a billion times, I think it's an A-518 ) started making a brief grinding noise when putting it into gear, either from D to R or vice versa, and occasionally hitting the N in between. It sounds a LOT like bumping the starter with the engine running. From underneath, you can even hear something winding down after the grinding like a pinion gear does.
John
