All yokes have a plug if you will at the end, so the oil does not leak out. Its similar to a frees plug. Some have a small hole drilled in the center, that would make it a "vented yoke" If you using a vented yoke, the output shaft must have a retainer with a o-ring on it to prevent fluid from leaking out the splines. Looking at your output shaft, you have a later model output that normally has the retainer installed. Yours is missing. Therefore, any standard turbo hydromatic slip yoke will work just fine, as long as its not vented.
I searched goggle and could not find a good pic...