Hi thundair and welcome to IRV2. I can't help you with the dipstick, but have you tried RV Salvage yards? Here is a list of many of them:
http://www.rvforum.net/SMF_forum/index.php?action=Parts
The dipstick from any RV on a 1996 Ford F53 motorhome chassis should work. The dipstick is provided by the chassis builder, so anything built on that chassis should be the same. Adjacent model years might also work (emphasis on "might"). The dipstick from a van or pick-up with the same engine probably is NOT the same length.
__________________
Gary Brinck
2004 American Tradition; 2007 GMC Acadia
Homebase in the Ocala Nat'l Forest near Ocala, FL