Female 3/4 NPT ?'s (brain fart on my part)

(I posted this in the main CNC forum too, as I am in quick need of an answer. Please forgive me Don.)

When threading using a G76 on a Haas lathe, do I program the X axis absolute value for the thread major at the back end of the thread after the taper, or the at the thread major at my Z start point?
(I have totally brain farted here)

I.E
(part previously bored with taper, and entry chamfer)
G00 X.85 Z.25
G76 X.998 Z-.75 K.054 D.015 I.0312 F.0714 A29

Last night, I used X1.061 (which would be the largest thread major @ Z.25
and BAD STUFF happened.

However, if I use X.998 (being the smallest thread major at Z-.75) it does not look right on verify.

OR am I being a total useless blob of human cells, and doing it COMPLETELY wrong? I am going on too few hours of sleep lately for any cohesive thought process!

Thanks,

Doug.

FYI, This was answered in the CNC forum.
For anyone who might want to know in the future, it is the TARGET diameter at the end of the thread.
Thanks again to you guys!
DC