Dave ,
What Star is trying to say is if your mower is rear discharge it will be a CT or CTH model Husqvarna .
Outside the USA the name "Craftsman" is not necessarily owned by Sears so for gear not sold in the USA one would not find it surprising for the IPL's to be ommited from USA sites.
In Aust Craftsman mowers are the property of Power Products , the whole goods division of Roy Gripskie & Sons and me not being a whole goods retailer, have no access to the Power Products web site . Chain saws are owned by Forest & Field and hand tools by yet a different company .
IF you are in Europe or the UK then it is similar over there .
So if Star was correct and you have the 42" deck then one blade would be 532 21 80 05-84 and using the look up method outlined previously you get
this page from Jacks Small Engines
Your mower will be one of those listed and then you can use either the CTH number or the long number starting with 9 to download the IPL from Husqvarna .
Before coming here and finding some very helpful people this was the method I had to use every day as we get a lot of US made mower, rebadged with local names so any chance of looking them up was non-existant unless you were part of the brand dealer network.