Treasury Records are by far the most underutilized records in genealogy. Pension Ledgers and pension payments are just the tip of the record iceberg. Treasury Records, RG 217, are the coolest records, but you have to dig for them.
Craig covers these and many other useful records in his SLIG course, "Post-War Military Records." For more information, see http://www.ugagenealogy.org/cpage.php?pt=339. To register, go to http://www.infouga.org/aem.php?lv=r&eid=12.