I have purchased front and rear Delco AC shock absorbers. For my 1997 Chevrolet Silverado K1500 the part numbers were 530-312 (front) and 530-189 (rear). Ride quality has greatly improved compared to the stiffer Bilsteins that have been fitted in recent years. The suspension now moves with the road instead of vibrating over bumps. It drives the same as before. Very easy to change, maybe an hour for all four wheels.