The lower packing part number is 251511139. Yes it is becoming very hard to get. McMaster Carr  #84765K122 (Abrasion-Resistant UHMW Polyethylene Sheet 1/8" Thick, 6" X 6" Sheet Size) or #84765K122 (Abrasion-Resistant UHMW Polyethylene Sheet 1/4" Thick, 6" X 6" Sheet Size) works very well for this. 
Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of J Stewart
Sent: Monday, February 20, 2012 7:00 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Rear Coil Spring Question

Yesterday while attempting to do my CV joints, I noticed that thin plastic collar under the coil spring is cracked. I've looked at a couple of sites, and I see plastic pads that say they go on TOP of the rear spring, not under. Then too, I seem to remember something about making these yourself using kitchen cutting boards? TIA, Jeff