Just curious because I'm seriously considering it.
The calculations show that I'll see 15-16 MPG out of this "Sleeper" if i get one.

The engine and trans would turn less RPM thus increasing engine/transmission life and add about 4 miles to the gallon on the open road.

That would extend my range by about 170 miles per fill up. (42 gallons)

 

looks interesting
Gear Vendors Under/Overdrive Ford 2-Wheel Drive 3-Speed Automatic.

 

Never been a fan. It is not that it isn't a good unit, but the whole 'gear splitting' thing and the expense and hassle make it not worth it to me. Granted the BBF has limited options, but an adapter bell and a more modern transmission (manual) is cheaper and simpler. The auto branch has *no* options for OD so you get what you get. 2K+ for the GV unit is just the entry fee. You have to shorten the drive shaft and possibly play with the mounts. Some people love it. YMMV.

 

I just got 17 MPG with 360FE/TKO-500/3.50 combo.

About the same entry fee as a GV but street-friendlier IMO.

 

How many years it would it take to recoup the initial investment in fuel savings? Probably decades......

 

Decades? No. If it's not being driven then there is no payback... it's all about miles logged.... But the payback is waaaay long. The fun factor is off the charts though.

At 10 MPG and $3 per gallon, it's 30 cents per mile. At 17 MPG and $3 per gallon, it's 17 cents per mile. A marginal "savings" of 13 cents...

$2,295 divided by 0.13 is 17,653 miles .....to pay it off.

 

I guess it then depends on how often and for what purposes you drive your truck. I'm not sure how many people dd their trucks here, but I guess I speak for myself in that it would take decades to recoup the cost :-)

 

That's not to mention the decrease in wear and tear on the motor and trans.

Besides, for me having 6 speeds will make this "Sleeper" even more fierce.

I have "Schooled" many young kiddies about laughing at an OLD truck.

Wanna Race?


LOL

 

The gear splitting is going to be the biggest benefit. Depending on your exact gearing, I doubt you'll see that much improvement in MPG.

I swapped from my C4 to an AOD and I might have gained 2 mpg. my overall drive ratio went from a 3.25, to a 2.14, to a 2.75 when I installed 4.11 rear gears. 3.25 and 2.14 got the same mpg. 2.75 is slightly better.

 

I have one in my '68 F250, mostly stock 360, T19 tranny and 3.73 gears. By mostly stock, I mean the only mods to the engine are an Edelbrock Performer intake, Edelbrock 600 cfm carb and Duraspark electronic ignition conversion. The engine is pretty tired but runs well. I see virtually no gain in mpg with the overdrive, it's a pretty solid 10-11 mpg either way and if I'm towing a fairly heavy load I can't use it because the engine just won't make enough power down that low in the rpm range to keep the truck and load at speed on the freeway. If I changed the cam it might help I suppose.

Personally, I'm not all that impressed with the GV unit. I got it free (well, in partial trade for some work I did) or I'd be pissed at myself for having spent the money on it. It's an older unit and needs to be rebuilt, the pump pressure is too low and it often drops out of O/D all by itself at lower speeds (well above what it's supposed to be) but GV won't sell the parts to rebuild it myself, they insist that I have to send it to them to be rebuilt, at nearly the cost of a new unit.