Iron is probably easiest: the 2.0 output transformer is a Speco that is mounted on top of the chassis with wires passing down either side through the plate. The 2.1 has a Bottlehead choke mounted on top (and a Bottlehead output transformer mounted below(PC-3 and OT-2, respective)). The wires for the choke pass through only one hole to get under the chassis. The 2.1 also has cooling vents on the chassis. If you're still not clear, post a pic.
