My thanks to those who replied to my search for D-ring leader tabs.
Here are a few sources that sell them:

Player Piano Co of Wichita, http://www.playerpianocompany.com/ 
Bob Billings, perforator@sbcglobal.net.geentroep
Richard Ingram, rollguyrich@yahoo.com.geentroep
  [delete ".geentroep" to reply]

I believe the above address are correct.

Jud Murphy
Longmont, Colorado