[FormulaLT1]

I don't think its all that difficult to install a differential or ring gear but due to the fact its a very accurate adjustment requirement. You have to make sure you don't screw anything up or you will find yourself replacing the whole rear end assembly. Thats why either watch a professional do it the first time or pay someone to do it. Also, yes you need to remove the cover. The plug will show you nothing but if a lite fluid drip. I was driving around my Formula for like 2 -3 months with a rear whine and clunk from take off which turned out to be a chipped ring gear. It was a little annoying but nothing major happen but something major could happen if that chipped piece of metal found its way into a bad spot. So the sooner, the better.