in my experience, in 1987 my unit was starting to upgrade some of the M2A0s to A1s. There were vehicles with the larger bustle rack and some without. Same with the smoke grenade storage boxes.
My company, at the time of my departure was still 100% A0 models. Other companies were in process to be upgraded. these were the same vehicle, just brought up to A1 specs.
My unit was Dco 2/30 Inf 3rd ID, Schweinfurt Germany. jan 86 to june 87.
oh, and our Battalion was still 100% forest green, no 3 color nato cammo.