Steering coupler

OP, you need to clarify-
Are you looking for a factory type coupler, a coupler rebuild kit, or an aftermarket U-joint?
Coupler rebuild kits are pretty commonly available, but can be tricky to install correctly your first time. There's some good tutorials in the "How To" articles section of this forum.
If you're looking for a U-joint, do you just want a straight up U-joint or a vibration reducer?
Also be aware that if you use an aftermarket U-joint or vibration reducer, you'll need to cut and shorten your steering column an appropriate amount, being careful to keep factory indexing (or your steering wheel will not be on center).
Input splines for the manual box are 3/4x36, column size I believe is a 3/4 DD.
Beware of cheap internet U-joints, they are just that- cheap. This IS your steering, after all. Stick with Borgeson, Ididit or Flaming River.