Joncs25

I've always heard that a 2wd 4L80 that has a fully splined output shaft can be converted to 4wd use by cutting down the shaft to the correct length. I purchased such a 2wd trans, adapter, and NPG261 transfer case. As I was taking measurements to get the output shaft length right, i noticed that it looks as though the snout of the TC input shaft will hit the tapered section of the trans output shaft before they are fully mated up. Photos below for clarity. Anyone run into this issue before? By my measurements, i would need about a 5/8" spacer to make sure everything will bolt up properly.

1FastBrick

iTrader: (17)

The 4x4 output shaft is different in that area.



There is more to it than just the output shaft though...

chris99gmc

I believe you need the output shaft housing as well. And a plug for the lube feed that (used to) go to the bushing in the tailshaft.

I’m currently starting to compile the rest of the parts to do this conversion as well.

Joncs25

The transfer case adapter was bolted on to the TC in the photo i attached. The orificed lube plug has already been replaced with a solid plug. I spoke with advanced adapters and they said that i would have to replace the trans output shaft with a 4 wheel drive shaft. My only other option would be to have a custom spacer built to add in another 5/8" between the two.

jonnyboy

iTrader: (3)

I know this is an old, and it would've saved me some time!!
However, you do not HAVE to change the transmission output shaft for this to work; it would be ideal.

On the 2wd 4l80e, you have to ensure you have the fully splined shaft, and cut a bit off. I think the 4x4 version is 3" or so. I measure tcase, adapter, etc, and made my cut. You also have to install the plug into the office that oils the 2wd tailsshaft. From here, with the adapter, my tcase bottomed the splines out on the tranny shaft where the splines stop and that buldged part is. The spacer on the adapter wasn't an option for me, as on a tahoe with the short torsion bars, the crossmember is very close to the tcase with a 4l80e.
the fix? Cut part of the transfercase input shaft. measure measure, measure, and make the cut. Ideal? No, but it works.

Also, my measurements for driveshaft shortening are that 1.25" needs to be removed. I have never seen that measurement listed in any thread; my 4l80e with adapter and nv246 tcase is 1.25" longer than the 4l60e with adapter and nv246.

Used the duramax front shaft that has been mentioned on several other threads. Also, the speed engineering tubular crossmember is great.

Maybe this will save someone some time.


Here is a helpful photo.