1966 Gearbox

The 64-66 gearbox was externally identical whether it was 4- or 5-turn.

Before trashing a $400 part, you should adjust it as per the Ford manual. I'll bet in the last 40+ years it's been adjusted "0" times, and a bearing and gear preload adjustment would likely reduce your play about 90%. Don't try this without the book, though, improper adjustment will destroy the gearbox, and might kill you. Re-filling it with proper steering gear grease wouldn't hurt, either.