Also known as Human Soldiers, Human Grunts were probably the smartest and coolest of all the H-L enemies. These guys communicated with each other, they could flank you out of hiding, and most of all, they are a team! The changes to these guys were mainly there clothes and there weapons.
In this pic, you can see that they're holding an old weapon and they just look slightly different
From the dead bodies you can see that at that time there was probably only one death sequence
Notice the old shadows
These are pretty close to the current ones
Notice that they are all in the same sequence
This one is probably older than all the ones above, they have old weapons and different clothes
Technically, this guy is also a Human Grunt, but in old pics he looked to be almost separate.
See how he is so much different than Human Grunts in old pics, and he has a cool looking chaingun
A close up of him
Another pic of him