I just put in my order for a 07 E 350 XLT Van 6.0L. 5-SPD. I want to get the best mileage I can get. So the 3.55 w/out L slip, or what I ordered a 4.10 with L Slip, and the only trans option a 5-SPD AUTO. No 6 speed for vans. I won't be towing with it at all. I'm stuck, I like the LS but I think i'm about to take a hit on mileage for it. I hope i'm wrong! Should I get it?