How hard would it be to take something like a late model (1999) 4L80E 2wd transmission and make It work for a 4wd application? Electronics and internals the same?

 

The tailshaft housing and shaft will need to be replaced.

 

OTHER THAN THAT, THEY ARE THE SAME?

 

Going from 2WD to 4WD is easier than going the other way. You will need an output shaft assembly. The 2WD version has a reluctor ring on the output carrier and a rear VSS that the 4WD version does not have. Leave those components in the trans but the rear VSS will not be used. (4WD versions have a plug where that VSS is)

4WD 4L80-E output shaft is 24204291, $186 list.

 

Or you could use a divorced-mounted transfer case with the 2-wheel drive tranny. That would eliminate the need for a different tailhousing and output shaft, and you have a better selection of 'cases to choose from.

 

I already have 2 241C cases. One for either transmission I was considering. 4L60e and the 4l80e. A 27 spline and a 32 spline case.

 

Thanks for giving me that info and the part number, I apriciate it.

 

Now that I have the transmission, should I have a shop replace the output shaft or is it something that's easy enouph for me to do? I've never done anything to a tranny other than replaced the filter, O ring, gasket, and fluid. Does everything from the pan up have to be removed to remove the shaft?

 

Let me say that you will have to remove the valve body to get to two bolts that hold the center support and OD clutch, after that you will need to gut the tranny completely to gain access to the output shaft.

Taking it to a shop is risk in its own, you need to ask yourself are they trust worthy, will they get pissed if you watch them tear it apart.

With the knowledge you say you have I would take it to shop, but do your research on the shop first. I know of a excellent shop in Amarillo, TX, I have used them for years for parts and transmission work (depends on do I want to do it myself).

 

Crap, if I knew that I might have just waited for a 4wd transmission. I'm guessing that it is not going to be cheap to replace this output shaft. Any idea of how much a job like this will cost in labor?