I DON'T KNOW ABOUT A CAP, I PUT A TONNUE COVER ON MY 2005 FOR $130. IT KEEPS 99.99% OF THE RAIN OUT OF THE BED. I THINK THE ONE YOU NEED IS EVEN LESS. EBAY!!!!!!! SHIPPED TO YOUR DOOR IN 2-3 DAYS.IF YOU WANT TO SEE MINE, GIVE ME A SHOUT.(SWEDESBORO)
Caps got hard to get. I was looking for one for 02 silverado and every place i called had to order one. 2 to 3 weeks i went to canada last weekend and wanted it for that. There is a guy on ebay that sells used caps. He is over near Pottstown, pa and when i talked to him he had over a 100 used caps. Put in toppers on ebay and he will probably come up if i find his number i will get it for you.
you might have gotten lucky i found the guys number its 610-635-1860 i had it in a note book on my desk. He has a ton of them from the pics on ebay he had. It looks like he gets them from a car dealer who takes them off or a junk yard/insurance yard. Worth a try he didnt have what i wanted but he had one that would fit my truck for 450 but then i would have had to paint it and at that point i might as well buy neww for 1000