4.1 diff in an auto?
 

How hard would it be to switch, is it a direct bolt on?

Nice name for your homepage:D It should be a very simple switch to do. Do you plan to do it or a shop?

I plan on doin it, i dont trust anyone touching my car, a buddy of mine has a lift if i need it, but i plan on doin it in the driveway like everything else... Just kinda wondering if it is a direct bolt on.. if it will bolt up to the drive shaft? Has anyone else done this before?

You should be able to just swap the ring & pinion - I have thought about this and imho it is not worth the hassel just to go to 4.10 - get a 4.30 or 4.33 Ring & Pinion - w/ the 4.30, OD on the Auto will be about the same as 5th Manual and 1st (a) will still be taller than 1st (m) I have a chart comparing Overall drive ratios A/M w/ the various rear end ratios at home I can post later.

What will probably be the top speed on a car w/ 4.30
r & p and the 4-speed auto??