So I decided to do the whole E85 in my 97 4.3 and guess what, after a few tanks of fuel it was running good. I started off by mixing 2-3 gallons in with the regular fuel. Then I went to 50/50. After a few more tanks I went to straight 100 E85. You say it can't be done, I called and talked to a few places that make kits for cars and sure enough they said some 4.3's don't need any conversions. Then after a few days something happened, my fuel pump died. Go figure, all the crap from all over the world finally came up and killed it. When I changed the pump, my tank was super shiny inside but my pump was stained dark pee yellow. I later won a free kit on FB from the company so I can do the hardwire to my engine if I feel like doing it.
On a side note, why did the military and gov't buy tons of flex fuel vehicles when they don't either sell it or use it on base. I know in the late 90's we had propane trucks and again they had to go off base just to fill up. Talk about a waste of time.