Hello guys, I am currently rebuilding the original 352 for my '67 F100 LWB and I'm in the hunt for a highway solution in the transmission department…

When this is back together I plan for it to be a daily driver and one of the coolest commuters that will be seen in the parking lot at work. Amongst all the Prius, foreign jobs and Yuppie vehicles, this thing is going to be so cool.

But guys, I need another top gear in a bad way. I've thought of a couple of solutions and wanted to run them by the forum and get the collective knowledge that only a forum like this can bring to bear on a situation like this.

Option 1: find an original overdrive transmission for the truck - it is currently a manual 3 speed on the column. This would need all the various control pieces, relay, vacuum line and port somewhere on the manifold, override pull lever/cable, etc. I would also have to shorten the front portion of the driveshaft between this trans and the middle joint (two part driveshaft in the long beds). This option would keep the truck sort of original in that you could order this truck with this option when bought back in '67.

Option 2: move to a floor based shifter and drop a 4 speed or even a modern 5 speed in there. - This option would require the column to be cleaned up replacing the shifter collar with a smooth (no shift lever hole) one, maybe slight mods to the tunnel area of the floor to clear the shifter and tranny?, and the obvious purchase of the said new transmission, and resize of the driveshaft.
I like this option as the trans would probably yield the best highway gearing with a true overdrive and I'm in control of all shifting, but this definitely goes away from keeping this truck original.

Option 3: You guys already know this one…. go to the Auto Trans like a C6 or even more modern with an OD. I don't really want this option personally because I kinda like shifting gears, but I could do this and have done this to a '63 I once owned.

Chime in, let me know if you guys have pros cons that I haven't thought of here and if anyone knows where I can find the trans for option 1, I'm in the market…

Clay

 

its honestly much cheaper and easier to swap in a higher gear ratio in the rear end most places the rear (pumpkin or carrier or whatever you wanna call it) can be bought for $50-$100 at a salvage and you can hunt around for some taller tires too since they essentially do the same thing although both of these fixes will make your speedo read incorrectly but you can replace the speedo cable gear for pretty cheap $5-$10 range IIRC...... i had a problem with my 66 rapping too tight on the highway for fuel mileage so i swapped in some 2.75 gears and 265-75-16's and my FE i had built for it got an AVG of 16 MPG and i have a years worth of mileage and receipt's to verify it it was a hell of a lot better than buying a different trans (just going from 235-75-15's up to 265-75-16's gains you a 6 mph at 65 mph) here is a nice website for playing with tire sizes 235/75-R15 vs 265/75-R16 Tire Comparison - Tire Size Calculator and from my experience's you can run a 285-75-16 on the back of a 67-72 and still haul over a ton of firewood without rubbing

 

2x with smoken above... a pumpkin swap is the best bang for the buck.

But if it's a commuter, then a rear gear of 3.70 or numerically higher coupled with an AOD would provide the best of both worlds in terms of off-the-line acceleration with long legs for highway cruising.

Here's gotta-know info on the AOD: Ford AOD Overdrive Transmission | Hemmings Motor News

 

Was going to ask about this. The easiest, is just basically swapping out the ring and pinion gears in the pumpkin?

 

Even easier than that.... find a Ford 9-inch, 28-spline gear carrier with your gear choice (a "drop out" or "third member"), disconnect the driveshaft, slightly withdraw the axles, and remove and replace the carrier.

I suggest verifying your current gear ratio and spline count before heading to the salvage yard... a 2.79 or 3.00 gear is highway-friendly.

 

Thanks for the replies guys. I kinda want that off the line power as well… I'm afraid if I made the gears taller and the tires taller to active the RPMs I want (btwn 2000-2200) at 70 mph I would be riding the clutch to get it going; especially with a load or pulling a light trailer which I may do… Again, not knocking that solution and I may go for it, but want the best of both worlds if I can get it! Thanks for the link to the AOD link HIO.

 

Hm, the warranty plate says axle code 11, the tag on the differential is still there but pretty tough to read even after wiping it down with oil. It sure could use a fourth gear on the highway, just like the OP says.

 

I have a t45 with a 3.70 which works out to 2100 @ 70
I understand there are kits to mount one of these to a FE combination.
The weak part of a t45 is the input shaft and does not like "side stepping " the clutch. Other than that it should work out for you once you get the driveshaft made up. I would add a aftermarket shifter with the adjustable stops to keep from overshifting and damage the syncronizer rings. The backup light switch mounts on the side of the case. Start looking

 

I swapped an AOD in my truck. 4.11s with 31" tires and AOD will be about perfect. Ive got the original 3.25 gears right now and it's too tall.

 

i have 2.75 gears and 265-75-16's in my 66 and i regularly take off in second gear in my 435 np even with over a ton of wood in the bed (which is 3.34 to 1 gear ratio and i can break the right rear tire loose with the same load) compared to the 3.00 to 1 gear ratio in the 3 speed you should have in your truck (which the c6 in comparison is 2.46 to 1 in first gear IIRC) so if you went with around a 3.00 gear you should be just fine and not have to "ride the clutch" here's a little inspiration just to show you what all i did on a regular basis with my 2.75 gears and my setup

 

Warner T-85N 3 speed O/D: No vacuum line or port required. Would need O/D kickdown switch, relay, cable, wiring harness.

But, all these parts are obsolete, very expensive when found, so IMO...forget about it.

Swap the 9" 3rd member to a higher numerically ring & pinion like 2.75, 3.00 or 3.25.

But, not all 1967 F100's have a 9, some have either the Dana 44 or Dana 60.3. integral rear axle.

Dana's have an inspection cover, the 9 does not.

AXLE code stamped on the 2nd line of the Warranty Plate, located on the left door face below the latch.

 

3.25 gears with 31" or 32" tires is an alright ratio. 3.00 with 29-30", 2.75 with 27-28"

 

Or if you have a feel for a clutch theirs the dogde/chevy Nv4500 5spd over dive tranny
which will give you good hwy gears for the over 50 mph driving range with out winding your engine up so high..

Many options but they all are at a cost:

Orich

 

Go TKO!!

 

In about 78-79 Ford used a version of the old cast iron toploader that had 4th gear overdrive. They were used in light duty pickups and vans, maybe a few cars (not sure). While not as stout as the old toploaders they will perform just fine for normal driving. I regularly see them for $100-$150. If you get one with the shifter, the hole in the floor and modifying the driveshaft should be about all the mods required. Pretty sure it's a bolt up.