Judging by the large spring antenna in the back, I'm guessing it may be one of the 1st gen units w/ the clutch system. Does the barrel elevate via the radio or can you move it by hand? Does it have one motor to power the tracks or two? Is there a black plastic box hooked up to a servo?
I ask because there have been a few revisions to this kit made by tamiya and the older 1st gen units have not been in production for many years. Either way nice find.