Joe, your stock fixture probably uses either an 1141 or 1156 incandescent bulb, either of those are around 400 lumens give or take. That makes this LED fixture only about 1/3 as bright.

I have found LED's to be tricky. They really fall into the "you get what you pay for" category. I bought a few different styles and types of cheap LED bulbs on Ebay to try in my interior fixtures. None of them were even close to usable as far as getting as much light as the incandescent bulbs. The ones that do get close are $10 to $15 per bulb and I need 19 of them. So that's out. If I did a lot of dry camping maybe.

You can not go wrong with an extra light.  Personally I was thinking I want to put one on the street side of my RV for when I do some things over there.