Went to do the tape mod on the slider door middle body track today as I had purchased the tape already. Started taking things apart to clean the last bit of track at the forward end. Was proving difficult to get the latch assy out. Was looking at the new plastic "guide" at the rearmost end of the moving latch. Remembered I had a nylon ball bearing pulley inside that I purchased from ACE hardware a few months back for another project - went in and found it - turns out it is a perfect fit (raises rear of door by about 1 millimeter). - just enough to lift slider metal roller buried inside the latch off the metal track. So, now that part of the door is very quiet. Next is to attack the bottom rollers. Here's a few pictures of the roller mod - remember this is for pre-85 vans only I think.  

http://www.pbase.com/spacecommander/image/151583637

http://www.pbase.com/spacecommander/image/151583639

Hope this helps somebody. Took all of about 15 min to do all this including determining washer spacing.

Tom

'79 Mercedes 300SD "Green Hornet"
'84 Westy Vanagon "Spiny Norman"
'86 Alfa Romeo Spider "Dinsdale"
'98 Mercedes E320 wagon "Silver Hornet"