Here are the roof rack mounting kits for Ford applications:
MKEZ34 Excursion, Roof Rack Mount / 1997-2002 / 52"-55"
MKEZ34 Excursion, Roof Rack Mount / 2003-2004 / 48"-50"
MKEZ34 Expedition (Roof Rack Mount) / 1997-2006 / 52"-55"
MKEZ67 Escape (Standard Roof Rack Only) / 2001-2011 / 43"-50"
MKEZ67 Expedition (Low Profile Rack Mount) / 2005-2006 / 50"-55"
MKEZ74 Expedition (Low Profile Rack Mount) / 2007-2017 / 52"-55"
MKEZ74 Explorer, Roof Rack Mount / 2011-2012 and 2013 Police Interceptor Utility / 52" -55"
MKEZ84 Explorer, Roof Rack Mount / 2011-2012 and 2013 Police Interceptor Utility / 43"-50"
Source:
http://www.whelen.com/m/models.php?prod_id=75
MKEZ34 is drawing number 62849
MKEZ67 is drawing number 64253
Here's an MKEZ74 on a 2009 Explorer, credit to member rwo978:
https://elightbars.org/forums/threads/whelen-hawaii-strap.19310/
If you decide to mount it to the roof instead of to the roof rack, an older reference I have lists the following strap kit for your application:
MKEZ55 63384 FORD EXPLORER 2002-2010