the best way to do what you want to keep your power down low and cruise super nice on the freeway only takes two words: Gear Vendor

keep your lower gear ratio so you got power down low still. and use your gear vendor for the freeway.

take your 1 to .65 (roughly) that your 5th gear puts out, and put another 1 to .6 behind that. that'll put you at like a 1 to .4 final gear ratio on the freeway. those gear vendor units are killer

 

I will have to agree with ya. The Gear Vendor units can't be beat. I borrowed a Dodge 3500 with a Cummins, a NV4500, and a gear vendor OD unit that belongs to a cousin. I was towing 9000# and averaged 20.4 MPG. I couldn't hardly believe it, and rarely had to come out of 5+. I will be checking out the Gear Vendors.

I never planned on putting much $$ into a 1984 truck, but it is a rust free from Arizona, and I consider it a keeper. I have lots planned for it now. Still much cheaper than a new ride.

I hauled 3 ton of stone in it today, and it felt like there was nothing in the bed. That was with the gas 460. I can't wait to feel the same load with a Cummins under it.

 

Today's the day!! Sold the 460, and it's coming out today. Still trying to find a tranny. I can't wait to get this thing going!!

 

Well,,, I just set the Cummins down in the Ford tonight. TIGHT!!! I have the back valve cover just under the rib on the firewall, by maybe a half inch. That lets the fan clear the radiator. I have it sitting about 1 1/2" above the TTB crossmember. The turbo clears the AC box by about an inch, and the exhaust is gonna be just as close if not closer, where it comes out of the turbo. Will this be a problem being that close??

NOW THE BIGGER PROBLEM: This engine has a vacuum pump with two round "bells" mounted between the timing cover and the power steering pump, and the lower "bell" part of the pump hits the steering box. Not sure what to do here. What if I "modify" the firewall so I can raise the engine a bit. I hear that the rib where the firewall dips back in needs to get the hammer treatment. I'm not a fan of beating the firewall to make something fit, but if it needs clearance here, I will notch it out and mig in a boxed recess in the firewall.

I know this is a common swap, so I hope to hear from someone that has been through this before.

Suggestions anyone??

 

For your transmission:
Going with a new rear end may be the answer. However if you change your gears in the 4th and 5th gear you may be pleasantly surprised. I changed my 5th gear in my 5speed dodge with 3.73 non positrac rear end. The factory gear ration was 1:0.85. The new gear Ratio is 1:0.73. result 70mph at 2000rpm. close to 21mpg on the Highway. Not bad from a 8100lbs truck.

 

Dont know if anyone told you yet but i did my fummins into a 91 f250 that had the ttb.... it sagged low but from what i could tell it drove fine. HOWEVER i dont have any real miles on it because i opted to do the D60 swap shortly after. My profile picture is of my truck with the ttb i used motor mounts from fordcummins.com and the engine fit (with a shoe horn) alright. As far as ttb to dana 60 the clearance for the motor really isnt different. The real difference is the weight the different axles can carry and the way that they can carry it as far as body roll and overall driveability.

 

I've been told that using a newer vane-type vacuum pump off an intercooled engine gets you some clearance for the steering box.

 

I like the divorced transfer case idea. I suspect you have room for it (an extra 30-36" or so) ahead of the fuel tank because you have the crewcab. Most Fords can handle 33" tires stock, so using something like 255/85R16s, with a governor spring, 4.10 gears should be workable. An extra leaf on the TTB springs usually puts the camber back to normal. The D50TTB should be strong enough for the cummins weight since it uses the same hubs as the D60.

It does. There are no diaphragms on it... just the hose connection. Very compact. It does push the power steering pumped back a bit though because it is longer.

 

I would stick with the ttb front end, unless you are going with much larger tires they are plenty strong enough. I would change your gear ratios however, I am doing the same swap on an 81 f-350 I have solid axles and 38" tires and am going to leave my 3.73's in the truck and see what happens, you will have stock tires and I think you will be screaming with 4.10's on the highway event with the gear vendors overdrive. You probably should go with 3.50's if you want to see good mileage and you will still have plenty of power. I would not do a divorced transfer case, get a nv4500 and either use the stock dodge transfer case or get a np205 and the adapter. Divorced is going to give you more things to break!

 

I just finished my 86 f250 fummins project and it sits about the same as it did with the 6.9 in it. I built my own motor mounts for free besides the cost of the rubber mounts and they are working good so far. I'm new here and have no idea how to do it or I would post some pics of them for you. I kept the old t 19 because of budget restraints but a zf is in the future because with 33's and 3.73s it's screaming at 60 mph. Anyways I just putt around and take my time wherever I'm Goin. It's definitely a beast compared to what it was even if it is slow. Lol