That would be the 2317 or 2317a, though going by the manuals I've seen some later units of this model # may not have the duo-trak as the parts went out of availability. -- Mr. Shannon Aldinger > There is a Peerless transaxle that is exactly the same as those used on > the > ETs, but it has positraction! A drop in unit if you can find one. I do > not > know the part #.