Ok, so my trusty 96 f150 finally died last month and I had to replace it quickly. I purchased a 1997 f350 cab and chassis with a 12 foot box on it with only 70xxx miles on it. It has a 460 gas motor, e4od trans and f5 (4:10) rear axle. I'm a contractor and I pull a 7k lb trailer plus materials in the 12 foot box (worst case loading). I get 5.5 to 8 mpg depending upon load and towing. I've been looking at a 97 f450 7.3 turbo diesel 5 speed to get instead because I was thinking the diesel would get better mpg. However, the f450 has a 4:88 rear and everything I've read says the mpg won't be much better than I'm getting now. Plus, the f450 has 199xxx miles on it, which I know is not a lot for the engine, but is for the rest of the vehicle. With me being in a vehicle with such low miles, and with diesel fuel being so much more expensive than gas, I'd need to consistently get 15+ mpg to make a vehicle switch make sense. I really don't need a diesel as I don't tow excessive weight, I'm just looking to save $$ at the pump. That said, I like the z-f5 trans way better than the e4od for longevity.

I guess I'm trying to see if I should just stay put in the truck I have and try to make some mpg improving upgrades or look for something else...maybe an f350 diesel with a 5 speed and 4:10 rear? What do you guys think?

 

With 4.88's i doubt that the F450 will get more than 12-14 Mpg, its guesswork on my part....If im wrong, id hope someone can correct me........that truck is designed for more carrying and towing capacity than you really need.....Now if as you have suggested you look for an F350 7.3/ 5 spd/4.10's that might fit the bill.

 

Towing 7k lbs behind a truck with a big box on it is going to beat up you mpg pretty bad with either gas or diesel. I bet that 450 would struggle to get 15 mpg empty, put a big wind catching box and a 7k lb trailer behind it and you'll be down around 10 mpg. The low miles is a big advantage, but the auto trans is a weak link. Adding a shift kit will help the trans live longer if it's still in good shape. Keep it cool and it'll be happy.

 

actually , i bet that 97 F-superduty (it is not a f450) has 5.13 gears in it, not 4.88's
4.88 gears in a F-superduty were rare.

 

I think you are better off with the low mile 460 over the a 97 F450. And if you aren't towing over 10k that is over kill. Now if you went to a 99-03 F250-F350 7.3 you can 3.73 or 4.10 DRW and get 16-18mpg empty and 10-14mpg depending on load towing. But if you are thinking of jumping to a diesel for mpg you better first consider the cost of up keep on a diesel is alot more than a 460. So I would also factor that in when you make a choice. Because for me I love my 99 F350 drw 7.3 but the cost of up keep and modds HURTS! I have 4.10 drw and I get 16-18mpg highway 14mpg around town if I keep foot out of it and 14-15mpg with 8500lbs towing.
Best mileage is straight highway at 65 mph / 2100rpms 20.2mpg