1988 560SEC, 161,000 miles

Hi. I got in my car today and put it in reverse and it makes a ticking noise, sounds like it is coming from the gearbox inside the car and sounds like when you were a kid and put a playing card on your bicycle tire and it made that click, click, click noise. It makes the noise in drive. The faster I go, the faster the ticking noise. Any ideas? Can I make it to the mechanic without ruining the trans?

Thanks! - Lance