The model designations for the 748 are all over the place - my Australian 748 has 748S on the machine punched nameplate riveted to the frame, but it is definerly not an "S". It is a 748E (no dzus etc) but labelled as an S. The real S was never sold here on Oz.
When I first bought my 748 I was confused as hell, then I found a usefull post on the forum which explained it for me. Plus 748girl chipped it to explain the aussie delivery situation. Thanks Jane!
Anyway, here is the quote I copied from that original post (which I can't find now - sorry). Hope this helps.
Variations
Ducati produced several variations of the 748, starting with the basic 748 Biposto (meaning "twin seat") in 1994 and then the 1995-96 748SP and 1996-99 748SPS followed as more powerful options. The SP and SPS engines were in a higher state of tune and also came only as Monoposto (meaning "single seat"), although it was possible to order the base 748 with a monoposto option, and were intended as homologation machines for World Supersport racing. Other extras over the base model included Ohlins rear shock and fully-floating cast iron Brembo brake disks. The engines also came with an oil cooler.
In 2000, Ducati revamped their 748 model line to include a third variation:
The base model was now known as the 748E, available as Biposto or Monoposto, with 3-spoke gold wheels and gold frame. Gone were the quick-release Dzus fasteners on the fairing, replaced with plain fairing fasteners, and the frame also had a fixed steering head angle. The rear shock was a Sachs-Boge unit with Showa forks at the front. This helped to keep costs down.
The intermediate model was known as the 748S. This had lighter 5-spoke Marchesini wheels in grey to match the grey frame, also retaining the earlier adjustable steering head. The rear shock was now a Showa unit with Showa forks at the front, making use of Titanium-Nitride (TiN) coating on the fork stanchions to "reduce stiction", which also gave it a gold coloring. The engine was a derivative of the earlier SPS, making use of the higher state of tune, and also included an intermediate exhaust system of 50mm headers connected to 45mm exhaust cans.
The top of the range model was now the 748R, Ducati's racing homogolation model produced only in very limited numbers. This engine was again a derivitve of the SPS model but with more tuning. The main difference is that the R model has an overhead shower-injector arrangement compared to the 748E and S model's traditional throttle bodies. As such, the 748R has a larger, two-part airbox and thus the frame was also different to accomodate this. The suspension choice was Ohlins for both the rear shock and front forks, although the very first models in 2000 used Showa TiN front forks. The engine included a very basic slipper clutch to ensure that this would then be homogolated for use in racing and also an oil cooler.
Ducati also produced a very limited run of 748RS machines, which were intended as full racing machines and as such came with no road-going equipment. The engine internals and components were vastly different from any road-based Ducati, using a variety of light-weight, high-strength materials making them extremely expensive to purchase, run and maintain. The RS came with a 54mm exhaust system and a slightly smaller size and gauge of Chromoly tubing was used on the frame to reduce weight even further.
cheers,
neil.