That is one of the servos for the application of the transmission band. No, it is not threaded in. It is held in place with a "C" clip.  If you look at the image circled in red there are two ends of the clip. A tool like a thin screwdriver is used to capture the end of the clip and then pry it upward and then outward out of the internal groove it sits in. You need to re-position the screwdriver as you work your way around. When it is removed one of two things will happen. Either near the end of the "C" clip removal the center piece will pop out with some force (it is spring loaded) and ATF will run out.  OR..., even after the clip is removed the servo cover will hang up and you will wonder how it will ever come out. Usually tapping on it causes it to free (with the same popping out results listed above). Basically what can happen is the "C" clip removal causes the servo cover to cock in the bore and hang up.


There is a seal on the outer cover and a seal(s) on the inner piston. Removal of the piston may also contain a rod.  Depending upon the band application hardware you may have to drop the trans pan and the valve body to re-position the attachment piece.  This is a generic description and the servo internally may be more complicated than I describe.

I used the term "generic" description because I did not know initially the specific transmission. But the servos all function pretty much the same.  My guess is that all the seals are showing their age and this one is just showing because it is external.

 However, as I stated there are internal seals that go with the servo pistons as well. If your going in that deep you might as well replace those too. I say that with the caution that the internals of the servo can sometimes get complex - but it doesn't look that way for the C3 (see image). Also, depending on the available transmission tunnel clearance you might not be able to get the servo all the way out before it hits the tunnel. You should be able to find the seal separately, but sometimes they are only available in transmission rebuild kits (as in you have to buy the whole thing). As best I can tell you have a C-3 transmission. The part in the image for the external seal is 362. The servo piston (seal looks integral) is 902. Note these are NOT the part number, but just the number in the image for illustration. You will need to find the part by application and the box brand stores might not carry it. It is possible that you will have to go to a transmission parts vendor.

All very helpful. Many thanks

Fred

Thanks Wittsend. 

Fred