Found it here: <!-- m --><a class="postlink" href="http://badgerandblade.com/vb/showthread.php?t=91556&highlight=aristocrat+guide" onclick="window.open(this.href);return false;">http://badgerandblade.com/vb/showthread ... crat+guide</a><!-- m -->
Solid baseplate (and therefore heavier) on the 16; diamond on the 66.
Crazy that this isn't considered a big enough difference to warrant a separate ID for the A.Jr., which came in both versions (solid and diamond).