Welcome to the community Deepcreek.
Google is your friend. See the third post in this link; straight from the horse's mouth.
http://moomba.com/msgboard/read.php?TID=659
The post is referring to a 2004 model, but i checked the pdf owners manuals for both 2002 and 2004 and the cages appear to be identical. So to answer your question 1 7/8"
You might email
[email protected] just to be sure though. It never hurts.
Cheers,
DKJ