This handy little ruler from the Gear Squad has been made available to help you properly identify your drive shaft u-joints.
Simply place the ruler's notched end against the tab end of your yoke, see where the ruler falls against the opposite tab, and that will identify your yoke.
To measure your u-joint, place the tab end against the u-joint cup squarely and view size at opposite cup. Due to age and wear, the caps may not be exactly on the line but very close.
Please refer to the u-joint tech sheet in the Gear Squad Tech Center more information.
Download Gear Squad U-Joints Ruler