Actually, it's the reverse. That ballistic shield was being issued in limited quantities prior to being mounted on the Abrams. Our scout platoon had one, and although they didn't care for it at the time, they never stopped using it.
Some interesting things about that picture. The gunner's turret armor's the older type (thinner, no angled rear), but they have the newer style gun shield. The nearest fella on the ground is wearing the VIC-3 style earcups that can be worn underneath the ACH. You can see the wire running around on the back of his neck, and the slight bulge of the speakers covering his ears. Of course, the lead truck's extra lights are not stock, but are added by the industrious crew/mechanics. And the extra antenna's, I know what they probably are, but they probably aren't a discussable topic.
There are things sometimes that you miss about having a well maintained vehicle to work with.
Jed