You'll need a 1/2 ton 4-speed u-joint assembly. A 4-speed yoke on the transmission side and a 1/2 ton 3-speed yoke on the drive-shaft side.

The 4-speed transmission will need to have the enclosed drive-shaft rear cover/housing.

Do you have the transmission rear-support/mount and the frame cross member (it was sometimes removed, but should be used with a 4-speed).