I just posted something similar in another thread. They used to include a bunch of them common adapters in each kit, but I guess they limit it now (maybe cost?).
Anyways, I used to have no issues getting replacement wiper blades to fit, but I just bought some Anco ones and they don't come with any of the adpaters we would need, anymore. They say our application requires wiper side adapter #48-08, but no one knows WTF that is, or where to get 'em from. I spent an hour looking on Ebay, for an Anco website, or anything else I could find to tell me where to get 'em again.
I did see NEW wiper arms in the parts store (wipers not included "of course"), for ~$22.... so I'm sure it's a way for them to increase revenues... stop providing the adapters for older applications and have you spend more $$ replacing a wiper arm that is still very use-able. Basically plan on ~$30 for each wiper arm/blade deal that you'll have to replace... what a scam.