Had the old ones stripped off in less than 10 minutes with the air chisel.

I knew the ones that were being replaced were from http://www.polyskid.com/ so that is the kit I got to put back on. I did not want to have to drill new holes.

Be careful and wear safety goggles if you have to drill new holes in your steel skids especially if your drilling from underneath. You just needed to make sure the poly skid is pressed tightly up to the steel one so the rivet goes through the steel skid before you drive the pin through the rivet to clinch it fast. I also used a blunt end in the air chisel to firmly seat the rivets. 

I'm pretty particular but do not go  quite so far as painting all the guards the same color every year.   In fact its kind of a good way to keep track of which ones have been replaced. I am pretty particular in that any worn ones get replaced with new ones not to mention that oddball 3 prong one and the ones that are tough to change are the harder silver type. I am pretty particular in that I put new sections on every fall before harvesting beans and check the hold down clips and wear strips too.