have not dug into Guide for that in awhile, but FYI see
http://hpiers.obspm.fr/eop-pc/
from which I then calculate 64.801 s rounds to 64.8 s
which corresponds to 6 double clicks on NIST WWV signal,
which also calculates to 64.8 s.
and Guide is also showing Delta-T= 64.8 s :)
open the Quick Info box.
(and I'm still running v.23feb 2005)

*************************************
Date: Sun, 05 Jun 2005 09:24:32 -0700
From: Laren Dart <sandman@...>
Subject: Guide Delta-T equation?

Hi Bill,

What is the current default Guide 8 Delta-T? I'm using the 28 April, 2005
version?