Right, when I replaced the ARB on my wife's 2002 52 Polo, the new one did not have any markings as it was a "revised" one. I think that you now need a new "revised" ARB from VW. Before just jumping completely to that conclusion, go onto
www.briskoda.net and look at the Fabia forum. There is a thread on this - use search and you should find it along with pictures.
If your car still has the original ARB fitted - I would have thought with white paint "swips" on it, you will find that the plastic ARB stops have cracked and slid sideways - that is what you are seeing - these "cups" are now u/s as is the ARB! IMHO, this ends up not being a diy job due to the need to drop the lower crossmember to get the ARB out - and that means a full four wheel re-alignment. If I were you, I'd track down your local VAG indep specialist and get them to source all the bits - ARB + mounting rubbers + maybe pipe clamps, and while they are doing this job, get them to replace the TCA rear bushes - but replace the normal bushes for Seat Ibiza Cupra solid ones. After all this work has been done you can put your wallet away for quite a long time. BTW the TCA bushes will need replaced anyway by now and Ibiza Cupra ones is the smart way forward - trust me. I have had to pay for this work twice with my wife's car - didn't know about the TCA bushes problem when I had to back down and let the dealer fit the new ARB. It was only while whinging on briskoda about these crap cars that I discovered that more work would be needed sooner or later!!! From the reg number, the dealer will know what PR code the ARB is - so will be able to supply the correct diameter one and bushes etc for that resived new one.
