I have an 05 e350 with 5.4 3.73's, tow 4300lbs loaded, cannot run in od, and not recommended in the owners manual. Tow in D, 2800rpm @ 65mph, 3100rpm @70mph, 8mpg no matter what I do. Do have aftermarket cone type filter (airraid) with air box mod, did add some more juice. Best tq at 2500-2700rpm this is the goal. Not sure what the engine curve is on the 93. I also looked into rearend change, but after viewing owners manual further did not pursue a $1500mod. Just learning to slow down. Hope this helps. I may go to one size larger tires, from 245 to 265 on next set of meats to increase speed a little more when in D. | 
