ok I am getting close to buying a van looking at a 07 5.4 350 34,000 on it asking $16.. or a 2012 5.4 350eb 31,000 on it asking $ 20 with flex fuel... what's the deference help....what is a better van for me? and thanks.

Flex fuel engines can run on pure gasoline or E85 (85% ethanol) and pretty much any mix in-between.

I may be off-base here, but ethanol can be aggressive on rubber bits, so the Flex Fuel motor has been designed for this, whereas a non-flex fuel motor is not.

http://en.wikipedia.org/wiki/Flexible-fuel_vehicle

__________________
2008 E350 RB passenger 4WD SMB penthouse
2013 KTM 350 EXC
2008 KTM 250 XCF-W
2003 Honda Element