alright i have 2 questions. on my 2005 automatic silverado 1500 there is a button on the shifter lever. it has a picture of a trailer on it. i was wondering if this was to lock a diffrential or if it is just a towing gear? also i have been looking for an ss bumper to put on my truck ive found the part its called the front bumper cover

but im confused because does this jst sit ontop of the factory bumper or does it replace it. it sounds a little flimsy if it just sits on top of it.

many thanks,
preston