Doing some recon on the options we want to order when we put in the order on our Yukon XL. Still kinda a toss-up between the AT4 and Denali. What I'm looking for is somebody who's got the fixed running boards, and somebody who's got the retractables. Trying to find the size (width of foot board) and position difference between the two. No dealers around us have the AT4 on the lot. When we were at the Chevy dealer, there was a marked difference in size and position on the Suburban fixed boards and the retractables (retractables wider foot board) - yet we saw an AT4 in a parking lot later yesterday afternoon and the fixed boards looked bigger than the Suburban... optical illusion??