This fork engages the throw-out bearing inside your clutch.
Smooth-case and ribbed-case shift forks cannot be interchanged, as the ribbed-case shift forks have a larger distance between the brass bushing and the fork arms.
If you are unsure, ribbed are stamped 22G168, while smooth are stamped 2A.
If you need new a roller throwout bearing while replacing your shift fork, click here.
Which shift fork do you have? This is a very common question, and not an easy one to answer. Of course, if the stamp is readable simply see above and you will know. If the number is illegible (which happens a lot!) you can measure from the center pivot hole to the small end of the fork. This will measure 4 and 3/8 inches on a smooth case fork, and almost exactly 4 inches on a ribbed. You can also see in the picture that the center pivot is much closer to the big end of the fork on the smooth fork. Having the matching fork to your trans is critical to clutch throwout geometry. I have had many a client ordering multiple pushrods and throwout bearings when the fork was the problem all along! So when changing from a smooth to a ribbed case, make sure you know when you call, we are going to ask!