The MG Gundam Ground Type, GM Ground Type, and EZ-8 were all released in very close proximity to one another (the first two in 2000, and the third in 2001). Because of this proximity, and because they’re all extremely similar in design, they share a whole lot of parts with one another. In fact, if you look closely and zoom in on this photo, there’s at least one runner stamped with “RX79(G)” and “RX-79(G) EZ-8”, despite the fact that the EZ-8 wasn’t out yet:
One of the consequences of this decision is that, in the name of cost savings, there is at least one bit of armor that’s supposed to be unique to the GM Ground Type, but is reused on this model too, even though it’s supposed to look different (it’s really not a big deal, but I just wanted to point it out)