I'm about to begin my 2.8 to 3.4 swap this weekend on my 91'
Trooper, first of I have to say that members of this site have been a great help in getting every thing figured out, so thanks a lot ya all.
I have all but one question left as to the procedure it self.
I've read all about changing oil pan from 2.8 to the new engine and how it often involves installing a new oil pick-up tube and all that. No one ever talks about why you guys are not keeping the original oil pan from 3.4 in the first place, is there a clearance issue in regards to front axle or any other components. From what I see Trooper's original oil pan is actually much taller than the 3.4 stock.
Any and all feed back as usual is much appreciated.

I'm not 100% sure, but I believe it is a clearance issue with the front axle. I think that the sump on the 2.8 sits back furter. It's not the depth that's the issue, it's the setback on the pan.

There's a lot of people on here that have done the swap and I'm sure someone who knows for sure why you have to swap will chime in.

I don't think that the 3.4 was ever installed from the factory in any 4X4, so you would have the same issue even if you were putting it in an S-10.