Those are the cars designations from Infinti/Nissan. All cars have a model designation that is not the standard name of the car. Example, Y33 = Japanese Domestic Market (people call that JDM) Cima and Q45 in the US. All car makers use these, so on boards like this it makes it easier to say G50 which was the Q45 from 90-96 which is very different then the FY33 which was the 97-01 Q45 and the F50 was 02-06 Q45...etc, you get it now.
As for getting the shocks/struts, call up 805-RARE-RIM (727-3746)Monday-Friday 9am-5pm PST,. that is a company called memoryfab, their website is
www.memoryfab.com. While you wouldn't know it from their website they have the ability to order KYB SR Specials directly from Japan. I bought mine from a guy that goes by the handle "onetongarage" who I haven't see much of lately, but memoryfab was cheaper, but were not around 4 years ago when I bought mine. They were getting like $500 shipped for them at one point, if you lucky they still sell them for that price. I can also consider doing Espelir or Tein springs at the same time as they work great wtih the SR Specials but it will lower the car significantly....if you don't want to lower it the stock springs are still fine with these shocks.
If you goal is to fix up this car and keep it a long time I would replace the springs, either lowering springs from new stockers. Try
www.everythinginfiniti.com, that is actually Scotsdale Infiniti and over mail order they will beat the prices of any local place plus you don't have to pay sales tax. They are supporters of this site, call them do not order via the web and tell them you read about them on this site and your a NICO member. They are usually pretty good...you can get the stock shocks and struts from them too, but they will likely be more than the SR Specials if Memoryfab still has them. While your ordering from them buy some new tension rods, front strut mounts (you should replace these at the same time) and while your there you can get other stuff you might need like brake pads, fuel filter, in-cabin filter, etc.
Now, if you just want to drive her until she drops for a couple of years then what the heck, who cares...but the OEM struts/shocks as you found out are very expensive. The KYB SR Specials fit great and will last a long time.