Waste of money to change them. Crank and cam sensors will very often outlast the car. They have no moving parts, and are basically just a coil of wire wound around a magnet (a variable reluctance sensor).
Wells isnt the best quality stuff out there.
05 Taurus SEL Duratec - my daily driver
04 Taurus SES Duratec - wifes car
95 Taurus GL Vulcan winter car
Toy #1 - 86 Tbird 5.0 (original owner) - LOTS of mods
Toy #2 - 88 Tbird Turbo Coupe - LOTS of mods
02 Pontiac Grand Prix GT
67 Honda 450 Super Sport - completely customized