The lane plastics are usually listed in inches - I have 5 x 2-1/4 inch and 2 x 1-1/2 inch if you want them. One tip -they are a lot whiter than the original so it may be an idea to replace the lot - I replaced all of them on my Jumping Jack -you can have the old ones if you want.I have 6 spare post screws as well if you want them. I cut the sides off the double plastics if needed. Also have 28 spare Accorn Nuts.
Check http://www.rtbb.com.au/catalog/index.php?cPath=40_111_136&osCsid=dafa48eabbe872aa8e10b5bf7b56f065 - I think Greg has them.What State are you in.
Millsy