There really are a number of differences, whether the changes matter to the owner is the main concern.
Wheels, brakes and spindles changed over the course of production
Cowl height increased and the windscreen changed about car #1200
Differential changed from the Ford 8.8 to the BTR/Dana about car #2068
Early cars had Ford brakes, then about car #680 Wilwoods were introduced.
A different version of Wilwoods were introduced about car #2700
Seat construction ant-sway bars, coil-overs, parking brakes, heater systems, dash layout all changed throughout the production.
There were a few frame changes to first accommodate the Mod Motor and then later the Coyote.
The steering wheel was angled forward to drop the steering shaft for the engine changes.
This information is from the Superformance MKIII Owners Manual produced by Mike Stenhouse/Second Strike.
Second Strike - the Superformance Owners Group
I was privileged to be part of the editorial committee.
Jim
SPF 1855 & 2584