TH350 from '84 GMC w/ 305. Trans appears to be leaking from the yoke on tailshaft.

[FreeTruck]

@NickTransmissions and whoever else may know:
I've done some searching and found a Facebook post concerning the same symptom, and I read people saying plug the hole with silicone and even plastic bags, but it sounds hokey and not to mention that hole is there for a reason from what I read. Thread is here.

There's also a couple pics of some kind of sleeve (#958 in diagram below, from FB thread). Someone in there said this part and an o-ring may be missing. If that's the case, who sells this and how much is it? Can I install this after removing the tailshaft, or does it entail a full breakdown of the trans?

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[ali_c20]

Sleeve: GM GENUINE 8654063 / ACDelco 08654063
O-ring: GM GENUINE 3764601 / ACDelco 03764601

~20$, availble at Summit, Rockauto and many other stores.
Only tail housing has to be removed for installation.

https://www.gmsquarebody.com/threads/2wd-th350-output-yoke-center-leak.31391/

 

[FreeTruck]

Awesome, ty for the info sir!

 

[FreeTruck]

Here's the nitrile o-ring in question for a bit cheaper than the AC Delco one. 54 cents apiece, versus $27.34 from GM!

FKM O-ring 37.69 x 3.53mm Minimum 2 pcs

38mm ID x 41mm OD x 1.5mm CS-Price for 5 pcs

oringsandmore.com

 

[FreeTruck]

I got that tailshaft off today to have a look inside, and sure enough, the o-ring was missing. I had the new one on hand and placed it on the tube. However, I noticed the speedo gear that rides on the shaft was not in the right spot on the shaft. I also found this clip loose:

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I believe it's number 849 in the diagram below. Does anyone know what this does or how to attach it?

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**Disregard, I found out what it was pretty quick: it is to hold the big speedo gear to the output shaft. I get to disassemble it all again, yay.

 

[xm20k]

The pin (yellow) goes in the hole in the tail shaft with the loop forward (bellhousing) and the gear slides on over it. The gear has a notch that fits over the clip when its pressed down it should then spring up and the two teeth grab the gear and hold it between themselves and the loop (green brackets). Looks like it is bent down may need to bend it back up some. (red arrows)

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[425HP409]

@NickTransmissions and whoever else may know:
I've done some searching and found a Facebook post concerning the same symptom, and I read people saying plug the hole with silicone and even plastic bags, but it sounds hokey and not to mention that hole is there for a reason from what I read. Thread is here.

There's also a couple pics of some kind of sleeve (#958 in diagram below, from FB thread). Someone in there said this part and an o-ring may be missing. If that's the case, who sells this and how much is it? Can I install this after removing the tailshaft, or does it entail a full breakdown of the trans?

You must be registered for see images attach

You must be registered for see images attach

The hole in the end of the yoke is so there will not be a vacuum issue when the spline threads are new. After they wear, fluid can get into the yoke and leak out of the vent hole. Since the splines are worn theer is no need for the vant hole and it will work just great with a plug in it. I always used a wheel cylinder cup and siliconed it in place. Works every time.