on my sprinter because of body line mine are about 4" in from back and they do a fine job of stabilizing the air...even tho they look like little cheap stick ons...never had one fall off yet....at least 6-7 years....don't forget to do the roof as well...the best you can...I had to have some bigger gaps because of sheet panel modeliing...Before you buy Airtabs do some research both here and the Airtab site. After doing the research carefully examine and consider the placement of Airtabs on a Transit.