There's a bunch of different length tailshafts / output shafts for the 4l80e: 3 3/4, 5, 7 7/8, 7 3/8, 8, 8 1/8, and 9" I think that's all of them.. But they are all 32 spline. There is also a conversion shaft available that's 27 spline for swapping a 4l60e for a 4l80e There's a site wittransmissons.com[/url] that has them all for sale for under $80 the 4x4 ones are the 3" and 5" ones I guess it depends what case/adapter you are running. The stock adapter to a 208/241 I believe is 2.5 inches thick and I'd imagine the 3 3/4 shaft would be the ticket once installed, but don't quote me on that my research is based on compatibility with a doubler which is a whole different game... Just figured I'd shed a little more light.. I gotta put a call into them (WIT) to see what shaft I need and to see if I am correct.