I have a 6.0 excursion that has been an awesome truck i just need a dually for my 42 fountain. Ive looked at some older 7.3's but they want lots of money for trucks with 250k+ on them. so im looking for a newer rig, really love the 6.7 but would prob have to wait a year or 2 for the prices to come down a bit. So that really leaves me with the 6.4 i dont want to mod it at all but need it to tow without problems. How have they held up towing? love or hate them? Any major issues?

I tow a 47 fountain with a 6.4 F450. I love it! Way quieter than either 7.3 or 6.0. I have no mods and it does fine.

If you buy a 6.4 and pull the pdf and a programmer it is a decent motor Just stay away from the f450 and f550 and you will be ok. My cousin has a 6.4 and it was getting 9-10 mpg's , after the pdf delete and the spartan program the thing has a hard tme finding traction and gets 20-21mpgs with no issues. just voids the warranty

The 6.7 seems to be a pretty good motor, just very pricey right now.

yeh our 6.4's were fine, no issues, but also dpf delete and tuned by Spartan and they not only hauled ass, but way better mileage. The 6.4's stock suck on mileage but that goes for the other makes as well as about that time is when they all started doing the dumb regen modes and dpf etc.

6.7 though rocks, such an awesome engine

Why stay away from f450 and f550?

I love my 6.4 it amazes me every time I use it. Mine is a 350 srw and I get 14-15 mpg. I had a 7.3 before and the difference is night and day. I'm waiting for my warranty to expire before I do any changes.

My 6.4 L was worst motor ever had. In shop every other month for 1-3 weeks at time. Got rid of it with 87k miles. One of the guys that works for us has a 08 6.4L sames as mine with no issues until 167k miles then it blew. And motor replacement is min $8k.

I have an 08 6.4 that has the Spartian tune & DPF delete. Great truck. In no way will it ever get close to 20 mpg as some claim when you hand calculate the mileage. The dash display will read that, but the programmer skews that reading. Figure more like 15 to 18 on really good days. I average 15 with a 4" lift and 37" tires.
I have 118k on mine and it has yet to be in the hospital for anything other than repairing the ignition after failed attempts to steal.
I'd sell it today for the right price.

No lift, but we got 18-20mpg easily hand calc'd on the 6.4 after dpf delete and Spartanized lol. Same thing for a friends 6.4. That was generally between 70-75 mph down here in flat FL lol. Stock was like 15-16 hwy, which the trucks ended up getting in the city after tuned.... factory tune/dpf/regen suck on the 6.4s.