I received my lift supports for my 1992-2000 Astro van, but one end is threaded. My existing supports are snap in.

The top end of the lift supports screws into the existing harness on your vehicle. This end on your Astro is integrated into the wiring system on your van and can not be removed. You need to get a good grip on the vehicle end and turn the shaft by hand counter clockwise to remove it and then clockwise to install it, then you would clip on the ball socket on the other end of the support to the ball stud on the vehicle.