Alright I am looking for anyone that has done this? I have an AOD right now in my EB mated to the stock dana 20. I have several concerns with swithing to an atlas 3.8.

One is with the tranny itself. I don't like not having a way to keep the tranny in 2nd gear. When I put it in drive it automatically shifts into 3rd gear.

I believe the atlas is 3.5 inches longer than the dana 20 so with the 1.5 longer tranny already it still shouldn't be that big of a problem yet. I hope.

I want the atlas so I can clock it up higher to put a flat skid plate on the across the bottom of the frame. Do I have enough room in the frame and will the front driveshaft have any issues with the tranny pan. Any help or advice would be appreaciated. Jake

The frame will limit how far you can turn the Atlas. Even with it turned as far as you can it still hangs down more than I like. The exhuast is another issue . I had to go above the frame and around on the drivers side.

I'm not sure how much you will be able to clock it - with my AOD and Dana20 - the front drive shaft barely clears the AOD pan when my front is at full compression - I have heard of a few people fully clocking the Atlas with other trannies in their EB, but I'm pretty sure they had to notch their frames.
As for the 2nd gear - sounds like you have a stock valve body - there is a trick you can use that the drag racers came up with - start is 1st then go to D to get it to shift into 2nd, then put it back into 1st. This will hold it into 2nd untill you go slow enough for it to shift into 1st (the internal governor restricts it from going into 1st at too high of a speed).
The other way is to use an aftermarket valve body. I am sure a few companies offer a manual valve body that would work, I am using a semi-manual vb from Lentech - 1st is 1st, 2nd is 2nd, D is 1,2,3 and then I have a electronic switch to enable or diable OD when in D.

As far as oil pan probs you will have less with the atlas than you would with the Atlass. The out put shaft is farther away from the center line of the Tcase then a Dana 20. And as far as clocking it you won't get it flat with out notching your frame and I think you may still not get it fully flat. And as far as the Atlass go for the 4.3 to 1 just my 0.02

Cool I will see if I can find lentech. How much was that valve body? Is it one from a AODE. I actually decided to go back with the c4 yesturday just because it seem easier. Plus selling the AOD will help finance the Atlas!

Lentech is at http://www.lentechautomatics.com/ they custom build all their valve bodies, but I am fairly sure they only make them for the AOD. Not really sure how much the VB was as I got a whole AOD from them , but I think they are in the $400 range with a 3 year warrenty.