I needed to have this kit to mount some new from ebay HD bags on my 07 Stoftail Custom. The kit is necessary to hold the bags away from the bike by about a half inch. Most dealers don't stock this kit, but after some looking I found one.
I was suprised to find the kit consists of four 3/8" stainless steel bolts 3" long (standard 16 TPI) and four spacers 1/2" wide each. The price was a whopping $39.95!!! Now I know why the HD catalogue does not show a picture of this part number.
I wanted to post this so if anyone needs this kit, they can get the exact same thing at the hardware store, or from your own bolt supply at home. If you have to buy the bolts, they are less than two bucks each. You can buy spacers, but I just used enough stainless steel washers to make the 1/2" separation needed.
The bags are mounted right and look good.
I just wanted to post this to help anyone who needs 90573-07 save some money and avoid the aggrivation of trying to find a dealership with the kit in stock.