Kevin, the part number is different from the Tbird but the controls arms are basically the same. They look a little different but are the same length and size. You don't have to be a gold member to get the better cost from Max, just tell him you're from LVC. I suggest checking out
Rockauto.com. They're pricing the T-bird LCA's for $58.79 a piece. Whereas the the LCA's for the Mark VIII's are listed for $130.79 a piece. You'll pay a little shipping but their prices are pretty competitive.
I recommend using either MOOG or TRW parts. Those are the OEM parts and you'll typically get the most life out of those. You can replace just the ball joints if you want. Realize thought that there is one bushing in the LCA's that cannot be replaced, so you're almost better off just replacing the whole LCA.