A couple of days ago, somone was able to help me count the number of
unique records + only count the value if it starts with "AM".

See below.

=SUMPRODUCT(SUBTOTAL(3,OFFSET(U2:U999,ROW(U2:U999)-ROW(U2),0,1)),--(U2:U999="AM"))

Now my next task is to see if the formula above can be tweaked, where
U2:U999 isn't predefined, but instead start on row U2 and go to the
last available row in column U.

Any feedback on this would be great.

Thanks,
Mike