It has been a few years now since I searched for these items but I ended up using MOOG upper ball joints with NOS boots. Upper shaft and bushing kits, I believe I bought at NPD. Be sure the outer shaft caps have the O-ring style seals. I could not find an exact same item for this detail and also, mine being Early-67, the studs that hold the shafts to the shock tower, fit loosely in the new shafts. That detail is likely another one of those supplier/running changes for the 67 model year and may not be an issue for your 68 Mustang.