Anybody ever have a 3 speed with OD in your bump from the factory? Just curious as my 68 f100 came with one. I ran it for quite a few years. Pulled about 20mpg with the factory 390 and 3.08 gears. It was strange, you could roll down the highway and let off the gas and it would drop to idle and you could throw the shifter in any gear you wanted, even reverse and it would just coast.

 

Wow I didn't even km is they made them.

 

I think they were available into the 72 model year but 69 is the newest pickup I've seen with one. Saw a 71 shortbed advertised once. Transmission was a T-85N, pretty stout and the R11 overdrive unit. Yes they would free wheel unless locked out but the part about putting it in reverse, well I guess I just never knew anyone who thought that needed a try. Also don't know about getting 20 mpg with a 390. Overdrive and 3.08 gears would be way off the power band and lugging like crazy I'd think, unless you had really short tires.

 

I need to check my vin tag. The truck also came with smog. Had the tubes that put the gasses back into each cylinder so I removed all that and had to plug all 8 holes. It also had some sort of governor on the the throttle. It would only allow you to give it a certain amount of throttle and it would stop you. The 20mpg was no joke.

 

1971 was the last year for F100's with 3 speed overdrive.

20 MPG is highly obtainable with O/D, in fact...

1965 F100 352 bored to 390 standard with T-85N O/D, '66 T-B 428 4V carb and manifold, dual exhausts, Cobra LeMans open air cleaner:

27 MPG on Route 66 rod run from Seligman AZ to Needles CA, average speed 45 MPH

 

Why the question mark face in my quote. I said I thought, which means I wasn't sure. And if you are going to hold every one elses' toes in the fire, no way can you just "bore" a 352 to a 390. And a partial tank of gas is never a baseline for mileage, it takes several tanks since just a couple degrees of angle where parked at the pump can throw off any calculations. Although no doubt it was real good doing 45. We remember the old Mobil economy runs where they got crazy good fuel mileage.

 

1981: I had the original '65 352 bored to 390 standard, then installed 390 rods, pistons and NOS crank.

I filled the tank in Seligman, refilled it in Needles. I owned the truck for 44 years, but this was the best MPG I ever got.

In fact, I think it was the only time I checked the gas mileage, just because everyone else was doing the same thing.

This was the original Route 66 that went thru Peach Springs, Goldroad and Oatman, not the later 'cut-off' version.