The T-500R was an experimental variant of the T-500 which had a vicious ape-like mentality and was designed with the purpose of psychological intimidation in mind.  The head was removed from the design, the limbs and fingers were elongated to grotesque dimensions and the chassis was black. As the head was removed, the "Reaver"  complex motion and heat sensors hidden on its chest and back allowed it to detect humans.  Its CPU was stored in its trunk and this creature possessed rudimentary intelligence autonomy not present in standard T-500s. It tended to wait, carefully hidden, in dark areas of ruins in a passive mode for an opportunity ambush the resistance.  Several times more massive and powerful than a typical T-500, the Reavers tended to prefer tearing humans apart by hand rather than to use weapons.  They were also equipped with speakers and a recording mechanism that allowed them play back the screams and pleas for mercy of thier victims to frieghten new targets.
 

The T-500I was an attempt to disguise the T-500 as a human.  The endoskeleton of the T-500 was thinner and more compact than a normal T-500, but the primative latex skin was utterly non-convincing.  Very few of the "infiltrator" variation of T-500 were produced as field tests proved unfavorable.