String Trimmers

Hi! I read on this site, and on the productinfo that 128JDX and 128LDX was the same trimmer, only difference was that the jdx was compatible with a grass blade. i got my JDX today together with some attacments that me and my dad who has the LDx was going to share, but the attachments only fit his, not mine. What attacments are compatible to both? When i check accessoties on both, the same comes up... My trimmer has a solid pin on the trimmer side, his has a reciever for a solid pin...