I'm not 100% sure but I believe the 998F01 and 998F02 were the two first Ducati race bikes with pressurized gas forks.
Contrary to the modern gas charged forks which carry the gas cannister on the caliper side of the fork leg, the early gas charged forks from Öhlins came with the cannister mounted on the forward side of the fork leg (opposite side of the caliper).
The bike in your picture looks to be from 2001 and if so it may have been equipped with the early gas charged forks from Öhlins.
That's a Factory 2000 bike so it's possible they have 42mm stanchions. Certainly the following year (F01) they were 42mm.
In 2001 a customer version of them became available to the non-factory teams - these were the aluminium radial-bottomed FG9760.
Molasses is right about the F01 and F02 forks - they were the first of the gas forks. I don't know the fork numbers but they had 42mm stanchions and slimmer outers too (56mm lower and 52mm upper I think, compared to customer forks' 58mm & 53.5mm). They had a gas cartridge mounted at the front onto which the mudguard was fixed. The cartridge is hidden behind the mudguard but you can spot these forks from the mudguard mounting screws which are much further apart. They had aluminium bottoms but magnesium top caps.
Good luck finding a set though!
The non-gas FG9760 radial fork is the nearest you'll get to them and they typically fetch somewhere around £3300 to £3800 a pair when you can find them.
I reckon a 10 year old fork with mag bottoms would best be used for show only. I heard that Ohlins themselves have tried to prevent their mag fork components remaining in circulation due to fears of them breaking in race conditions.
I might be selling some very nice radial Ohlins race forks soon, but if you want state of the art then there is a guy I know who is selling a set of FGR100's for €6000 euros.