I am using 4nec2 and am getting errors from the GM card. Wasn't there an issue
with these being a decimal instead of an integer?

Yes, it was and still is. 'Original' Nec2 does not understand the
Necwin+ syntax for the last field in the GM card when the 'x.y' format
is used. Within (modified) Necwin+ the ITS (imov)field with the x.y
format does move all (preceding) wires with tags from 'x' up to tag
'y'.

With default Nec2 the x.y field is rounded to an integer and all wires
with tags from 'x' up to the one just preceding the GM card are moved,
so no explicit 'end-tag' is specified.

When using Nec4 one can specify both the start- and stop tag- and
segment-numbers on four separate fields.

Arie.