My AT wont lock in, menaing I can shift it without depressing the brake. It also shifts from Drive to Reverse without engaging the shifter release button.

Is this the downward spiral for the AT?

Oddly enough I sat in another 1992 245 and it did the same thing. Something to do with that year?

Advice is appreciated.

 

This doesn't mean a downward spiral for your transmission. The shift lock mechanism is in the shifter inside the passenger compartment. If it were me, I wouldn't worry about it. Sometimes these locking mechanisms fail and rather than fix it, the previous owner may have just disabled it.