Have only brake lights not functioning- top center work, running work, blinkers work - so repair shop said we need to find the discontinued relay -- 8663490 --
anyone know where to find this or the replacement item ?

 

There are many relays with that part number in your REM and it is still used on new cars. Swap a relay from a different position to verify that's really the problem BEFORE buying any parts.

That relay is sold by many - google it.