I'm installing a new moog idler arm on my cuda, and when I took the old one out, it had one washer on the top and nothing on the bottom. However, I noticed that the instructions say to install the washer on the bottom side if the kit only comes with one washer ( mine only came with one). Will this have any affect on the steering if it's installed on the top vs the bottom side due to the slightly different installed height of the idler arm? Or am I overthinking this, and its just a spacer?

Who knows, thing to do is put the old on and measure down to floor, then do the same with the new, thats the only way to be sure. Do a search on mopar bump steer correction and you will get the idea.