Super 10 to RTOO swap

I have run a RTOO15613 behind a pumped up B model. They are not survivers. The super 10's have a .73 final ratio. The oo has a .62. You will see the boost and pyro go up in top hole which means your burning fuel.
I went to a RTLO20913 which is .73 final ratio as well. Got rid of alot of drive line noise, gained a low hole as well as a good retreat gear and fuel millage. I would say first make sure the ol CAT is doing what its suppose to then look at rears. It could have a little minor trouble causing the fuel millage

 

If you list the model # there are people on here that know much more than I do and maybe able to help you more. Super 10's have an auxiliary box and the driveshaft will be the same for a 13, 15', or 18, if the yoke is the same length.
Off the top of my head and all welcome to correct me.
11 series were never spec,ed with engines over 350 hp, not up to an E model.
At least some s-10's are about 30% OD and can be swapped with a RTLO15715C, also about 30% OD noted by the C. Many 13 spd's are about 13% OD but some are as high as 35?%, all in the auxiliary section. Front section OD usually runs about 18-22%. All that said to say you can spend a whole lot to gain very little in OD.
I have no ideal what to expect from an E at 75 mph and what is the best rpm maybe someone else can answer that. My class 7 truck looses 2 mpg at 78 mph over 68 mph. I learned to like 70 or less. How long will your fuel savings take to pay out. Just thank about and study it, good luck.

 

There was a thread bout a poor millage voo voo on here somewhere lol. We have a 99 379 with a 2ws set at 475. 3.55 rears tall rubber with an RTLO18915 .73 final ratio. Its a 5.5 mpg truck pulling a grain wagon. Had a very minor crack in the air to air and was a mid 4 ran like a top. The fuel millage is what made me go to digging I blamed driver then I took it out for a week and didn't really get any better. Didn't think I had a power problem till I changed the air to air it didn't feel like the same rig

 

How much boost do you see just cruising?
What is the pyro temp?
You can check the piping and front of air to air with soapy water,bump the rpms up about 1000-1200 and spray away.
A exhaust leak before the turbo will hurt mpg. With a cold motor,start the truck and run you hand around the manifold,you'll have a minute or two before it's too hot to handle.
Shine a light in your breathers,make sure the filters aren't clogged.

 

read over what woreout has to say on these topics. He's probably one of the best on here when it comes to fuel mileage and what a trans will and won't take power wise.

I've got a 600 that hasn't knocked down much for fuel mileage until now, I don't have 3.90s I've got 3.55s but until about 2 months ago I'd never seen better than about 5.5 now it's about 8...BUT I'm on lp22s from tall 24s from what I can actually figure on fuel mileage dropping to the 22s has actually helped kick it up to about 6mpg turning a higher rpm as opposed to my lower rpm that I used to turn at 65 boost dropped from 15psi and I dropped about 300 degrees off my pryro. it turns 1450 now at 65 pulls between 4-10lbs of boost flatland and that's running 90k instead of 80k. That motor is designed to run right at 1450 down the highway at 65 at over 80k and I believe they want it turning 1400 at 65 80k and under. I don't think the trans necessarily seems like it's running right in the sweet spot of where it should run, you start running 1200 or 1300 and you're going to be burnign more fuel and dropping gears like crazy on hills.

Kurt had a thread on this long ago with his C16 wouldn't pull more than 4mpg no matter what was done.

What file do you have in the motor?, also what are you pulling for manifold pressure, miles on motor? etc. all that factors into what is going on the winter fuel doesn't help matters either. I can see going to a regular 13 but that rtoo is probably going to more harm than good.