Tranny problem

1996 EB AWD V8 w/245K miles

Last night while driving home I noticed a whinning sound like you'd hear
with a bad power steering pump which changed pitch with engine RPM.

The tranny then started slipping - eventually getting to the point where it
wouldn't move the vehicle about a block from home.

Parked it on street overnight and checked it this PM with light.

The dipstick shows plenty of fluid, and no discoloration or burning smell.

Not getting anything when I hooked up the code reader either.

I'd also noticed a little slippage while accelerating earlier in the week.
Only recent major change was replacing a cracked radiator just after
Christmas.

Any ideas?

Vito