Hello guys,
I typically hang out down in the 6.9/7.3 IDI section, but I've got a question about an '03 F350 with the 7.3 and automatic transmission.
The truck is bone stock with 155k ish miles, and it's time for a transmission rebuild.

The engine is currently bone stock as well. I'm interested in hearing some thoughts about MPG-increasing modifications. At 155k miles, it's time to start planning for future repairs. I've spent a few hours searching the forum, and have had mixed results on ideas. I was thinking a better air intake and bigger exhaust to start. We're interested in better MPG, not huge power gains. Jeepers creepers, this thing is VERY powerful stock!

Just wondering what you guys recommend for modifications while the transmission is getting rebuilt? It'll only have to hold up to stock power (perhaps a little over stock power). We're interested in reliability. We have a truck camper in the bed most of the summer, tow a camper trailer sometimes, and sometimes haul a car trailer with a car or tractor on it. Looking for something that will hold up past 150k miles. The truck hasn't been driven hard at all compared to other 7.3 Powerstrokes I've seen.

We could hold off for another year to rebuild the transmission, but those darn starter bolts backed off about 3 months ago, and the starter chew up the flywheel! The bottom starter bolt thread was about 40% stripped, but we got a bolt to thread deep enough for clean threads. Unfortunately, the starter hasn't engaged the flywheel cleanly a few times since. It's to the point that we don't know if the truck will start if we shut it off!
So...while we have a shop replace the steel plate the starter bolts and the flywheel, we could have the transmission rebuilt. Knock a few things off the list at the same time.

Thanks guy, I appreciate your opinions.

 

I would think that additional trans cooling and gauges would be the things to start with, trans temp, pyro and boost.

 

A lower stall torque converter will net you a little more mpgs. With the diesels low end torque, you can gain more efficiency with a "tighter" TC. Also, tuning with quicker lock up characteristics and better shift timing would be beneficial.

 

For reliability, I would have your rebuilder install a Sonnax SC-4R100HD kit. It's a compilation of all the fixes they've developed over the years.

http://www.sonnax.com/instructions/SC-4R100-IN.pdf

Those are the instructions, and include each known weakness and potential problem addressed in the 4R100. You can get it for about $160.

Sorry, but I can't offer any advice for increased economy.

P