the new wear strips that i have purchased from my local napa store are 3 1/2 inches longer than the old ones that came on the sled. there is room on the rails for the longer ones, should i cut them off to go with the factory length or just leave them longer since they were worn off more at the back?

cut them back to factory, if you leave them to long when you pull the sled back the track will hit them.

I take it you have never changed sliders before... all aftermarket sliders have to be cut to fit!