Those if not to your liking are proactively changeble. He was asking if you had tried them yet!
I told him the deal.

 

Yeah, I've got to get with it!

 

Who's John Woods?

 

I've always wanted one of their underdrive units for my 3.55 geared trucks.

 

Duane, John Wood is a transmission builder who specializes in building Ford automatic transmissions that will hold up to heavy towing with a high HP modified 7.3L Diesel.

John Wood Automotive - *

 

I see, thank you.

 

I haven't re-calibrated for the 235s 85 16s yet but this is with the GV engaged.
And also why I haven't seen a mileage increase, you just drive faster.

 

That looks fun, I think I would wear a seat belt though

 

80mph at 2Krpm, cool

 

every time I think about an overdrive, I do the math. $3,000.00 for unit, that is 1224 gallons of fuel at today's price. if my mileage goes up say 20% ? I am currently getting 18.6 mpg not towing, had calculated every fill up since 2004.
that would put me at 22.3 mpg
at 18.6 mpg it cost .1317 per mile for fuel
at 22.3 mpg it cost .1098 per mile for fuel
a savings of .0219 per mile
divide the price of the overdrive $3,000.00 labor to install and driveshaft resizing by the savings of 2 cents per mile. it would take over 150,000 miles to pay for the overdrive.
will it last that long?

 

Your arithmetic is probably pretty close. However, most of us are operating our OBS trucks as more of a hobby than a business. In my case, and I'm sure I'm not alone, the fun of motoring down the highway at 80 mph and 2,000 RPM would be worth some money.

 

Actually, since he hasn't recalibrated for the 235s, he's going ~85mph.

 

True, I went from 215's on my dually to 235's and now 58 mph equals an actual 60 mph. I read thru that recalibration write up and I might do it or not. My new tires are actually .99 inches taller.

 

Myself, having 3.55 gears, would like to have an underdrive, and if I towed more frequently I think a $3000 underdrive unit would be money well spent if it were reliable.

 

I was seriously thinking about one but John Woods said he doesn't like them so that ended that. If he is going to warrant my trans for life I don't want to give him any excuses not to fix it on his dime.