The brace is sandwiched poly in next picIt would be wise to ground behind tail light on the suburban. The Pontiac minivan has grounding to the back door metal and then 2 straps connecting the door to the rest of the sheet metal. When back door is lifted up, the antenna goes up and over and lays horizontal and out of the way for loading etc.
Here is a link to aa1k who has put 300k+ miles on one of our antennas.
He worked 277 countries with 54 on 160 meters with the STANDARD 6-160 antenna. WWW.AA1K.US then click on MOBILE on left column.