Transmission Fluid Dripping From Front U-Joint

[c1500deathtrap]

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Either replace the o-ring, Seal the yoke with RTV, or get a yoke with no hole.

 

[ram1220]

On the oil seal #34 i had a similar problem on my '96 C1500 at the rear pinion oil seal at the differential where the drive shaft yoke is. If i have someone look up the part number it is the wrong seal and while it will press in to the differential, the seal id is too small for the drive shaft yoke.
I ended up taking measurements and going onto Oreilly auto web page and looking backwards '95 and back, and forwards '97 on until i found the different part. since i had already pried mine out I checked the dimensions with those on the webpage and back to auto store and bought it. I was frustrated too while i was at it but once i found the part it was all down hill and smooth sailing. Make sure you check OD and ID for the right fit. I hope you decide to fix this and keep your GMT400.

Again, the one you may need to replace is the O-ring inside the extention housing. Also not that difficult to remove. Here is also a good description of this. http://www.73-87.com/7387garage/drivetrain/yokeleak.htm

In a worst case you could check dimensions using National Oil seal catalog http://www.timken.com/pdf/7707_National Indust Seals Catalog.pdf
That's the same catalog the guy that designed the transmission would have used.

Thank you very much for this information. I am sure once I get the right parts I won't have an issue fixing the truck. It's extremely frustrating trying to find the right part. This was my Dad's truck so it has some sentimental value to me. Plus it runs as good as the day it came off the assembly line. I really hate to get rid of it.
I think you are right about the O ring since it only leaks from the U-joint. But I figured while I am in there I'd replace the oil seal.

 

[delta_p]

This was my Dad's truck so it has some sentimental value to me. Plus it runs as good as the day it came off the assembly line. I really hate to get rid of it.

Those are the best GMT400's and worth the keep. My C1500 happens to be the first and only truck I've owned, bought new in '96. Mostly a toy now but i still love it.

 

[kemo sabe]

I replaced my o ring inside the cup, but mine is still leaking. What would y’all do? Just seal it with rtv?