I went ahead and bought these floods for my reverse lights.
http://www.amazon.com/gp/product/B00GLLW3AM/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
All these style look pretty much the same size. I'll measure and let you know the size when I get them.
If I like them, I might try to do the same thing you are and replace my fogs. Thinking the spot version would be best for that.
Cool! Are you going to put then where you put the halogen ones?
I have new fog housings and fusion projector fogs to retrofit for my fog setup. Will have 6 hid projectors up front when all said and done lol