4L80E Tailshaft abomination???

[88Ironduke]

All,

Hoping the transmission god chime in here. I am collecting everything for a 5.3 LM7 and a 4L80E reman unit from an 03' Express van going into my 72' C10. The transmission has the typical fixed out yoke so after a quick inspection I order a counter bored yoke assembly to make the slip conversion possible.

New slip yoke from Denny's Drive shaft shop out of New York arrives in the mail. Its a new Sonnax unit counterbored for my application. Here is the rub, it seems I have found the unicorn in the Herd. This particular transmission has an output shaft housing that can also receive an external trans mounted E-brake if the vehicle is equipped. It has a roller bearing installed instead of the bronze bushing typically found. The new slip yoke fits the output shaft as advertised. I talked to the vendor and the slip yoke is correct for my application but the tail shaft is wrong.

Did the 4L80E receive different tail shafts thru the years or are they interchangeable, etc? I know the Turbo 400 shares allot of common parts with the 4L80E, might this be one of them? Need some help here.

Thanks
Paul

[Rich84]

I had a 4l80 with that tale shaft. It was from a box truck. I just swapped tail shafts with a junkyard unit if I remember correctly.

[Captainfab]

Why not just use the yoke that came on the trans and have a slip yoke put onto the end of your driveshaft? I assume your '72 C10 is a shortbed?

[davepl]

I assume there's no speedo output, right? The only tail shaft I could find for the 4L80E that had a mechanical speedo drive was $695 and totally custom! So I keep hoping there's a cheaper option...

[88Ironduke]

Originally Posted by Captainfab

Why not just use the yoke that came on the trans and have a slip yoke put onto the end of your driveshaft? I assume your '72 C10 is a shortbed?

Thanks all. I talked to my local drive shaft shop about my truck and options. Its a long bed 2 wheel drive and the current two piece shaft assembly needs to go in favor a stronger a one piece unit. I think arguments can be made either way but this is the path I have chosen. I didn't have a choice in the slip yoke conversion arena. The output shaft is not fully splined of course so It has to have a counter bore unit.

Still no cheap option on a speedo either.....

The abomination tail shaft housing is being replaced with a standard unit and hopefully be one more piece of the puzzle complete. Can you guys confirm if I need to removed the ( I assume lubrication
?) plug in the back of the transmission case body? Its currently got a small rubber/plastic insert and I am thinking it needed little lubrication for the roller bearings versus the bushing assembly..? Penny for your thoughts..

The only concern I have left is the current housing covers the end of the out shaft, its actually recessed in about 3/8" instead of sticking out like every other transmission I have dealt with. Hopefully GM used a standard length shaft assembly. Otherwise I'm in the

Paul