Rear bumper cover "slim" ?

[Cornerlot]

What does "slim cover" mean?? On the 2018+ S550 Mustang the rear bumper covers are listed as either "with slim cover" or "without slim cover". What is that actually talking about?

The Ford HVBOM and parts books for a 2021 Mach 1 call for JR3Z-17K835-APTM "All w/o sensors w/o slim cover. "

There is another bumper cover that lists for only GT350 and GT500 for 2015 - 22 that says "with slim cover" (FR3Z-17K835-AL) but I was under impression the bumper cover on the GT500 and Mach 1 were the same.

I'm looking for a used Mach 1 (or maybe GT500) rear bumper assembly complete with the diffuser within Texas. Shipping used ones via freight ends up the same price (or more) than a buying a new individual cover and diffuser from a dealership.

Sponsored

 

[Cornerlot]

My guess is that the 'slim bumper' is the GT350 version through 2020 which uses the 2015 - 2017 style bumper without the larger plate recess and without the center bump-down, both added for 2018+ on all other S550 versions.