I've just checked all over both. With a fine tooth comb.... Apart from the head, there is not a single difference between the 2 Megs....(mould wise that is.... Colour and deco is totally different)
And as such, A:Megs has a single symbol on the right side of the turret in Alt mode, and one on each shoulder in Bot mode... So a floppy panel would be useless and redundant on A:Megs, so the change to the mould probably wasn't justified...
Plus who knows what came first.... Toy design or story outlay.... They may not have known!
But I am wondering.... Is this a G1 Megs redeco'd to A:Megs? Or an A:Megs redeco'd to G1???