I've been amassing parts for a bit now, following a loose plan:
68-72 F250 looks
7.3 diesel power
Five speed manual
Ability to handle the power and weight

The last one has been the big starting point. My 69 F250 just could not handle the torque and weight of that 7.3. It's not a lot of torque, 375ft/lbs in stock trim, but the frame would twist and it would wheelhop severely when the tires broke free. It also did not feel right with a heavy trailer behind it. The diesel engine's oil pan was also interfering with the steering linkage on the 60s chassis, so I decided to go with an 80s frame. The rails are nearly twice as tall, and the steering linkage is in front of the crossmember.
The frames changed considerably in the 15 years that separate these trucks. Beyond the taller rails, the frame width is wider, the bed bolts are about 3" wider apart, and the standard cab wheelbase is 3" longer than the 68-72. Unfortunately there isn't much that can be done about the cab-bed gap, so here comes the twist- I grabbed a SuperCab chassis. A full 24" longer wheelbase, so the plan is to knock the rear off a 75-79 SuperCab, weld it onto the back of this one, and reskin it to match. I'll still have to fudge an extra 3" in there but it'll be easy to hide.
I know there were some aftermarket/coach built extended cabs but my goal is to make this one look like Ford built it. Body mount locations are going to be interesting, as there were some significant changes there as well.
The engine will be getting a turbo a little later on, for now I am doing some prep work towards that. Due to the difference in space available between the 80s and 60s, the turbo will be up front instead of the traditional location at the center rear of the engine.
For now, here's a pic of the donors. Bonus in the background is my Courier, which will likely be done before this truck.

 

Well I'm poppin' up the popcorn watching this one Jared. I'm all about "with a twist". Hence my 1994 Cougar with a 93 T-Bird super coupe front dog house. From the fenders and hood forward. A different build with a 7.3L,bigger frame to handle it, and the Key still On The Left.
That's Money right there Buddy.

 

Looks like you're in for some measure stick exercise time. I'll be following along. I don't know much about the Ford diesel engines, is yours one of the International-Harvester engines?

 

Jarad, I haven't kept up with chassis changes over the years. I know from my own Stanley 25ft measuring tape that the floor pans along with a few other items matched from 65 to 79. In 65 with the I-beams the front track was widened, and kept that way until 73 when the rear track was rematched in width. In 73 4in was added to the rear of the cab behind the rear cab mount for extra room. That is why the disc brake power steering upgrade is so easy.

I have asked this several times recently, if you are in depth on a build as you are why not work with a newer chassis that might be better suited for your idea? Cut block & weld until wheel openings and spacings are correct. They have been doing that to the big trucks for years. Look at a single axle tractor and one of those big stretch deals with a motel sleeper on it. The front wheels, engines and trannys are about the same on all of them.

If you know what you want to use then start with proper rails and go from there. I have a haunting memory of a complete naked mid 70s chassis all cleaned up that measured about 4 in longer than a 66 and I didn't know what to do with it (20 years ago).


John

 

This is a newer chassis better suited to my needs. This same chassis ran essentially unchanged from 83-96, the 80-82 chassis was dimensionally similar but had a few key differences, namely it had a mount point for a clutch z-bar, and was known as the Swiss cheese frame due to a bunch of lightening holes.
The engine is an 89 7.3IDI, with a ZF five speed behind it. It was not turbo in original form, but these engines can take 8-10psi reliably making quite decent power. Stock is 185hp and 375ft/lbs, 250hp and 450ft/lbs is easily achievable.

 

Front cab mounts of Dentsides are in the same place as the Bumpsides. Dentside rear cab mounts are a different width from Bumpsides, as you mentioned. From the back of the cab rearward, Dentside F100-F250s are 4 inches wider than the frame on a Bumpside, --except for Dentside Highboys and Dentside F350s. Their frame rail widths are the same as the Bumpside F100-F350 rear frame widths.

 

Radiator support mounts, cab mounts, and bed holes are all in 100% different locations between these two trucks. The front axle is further forward in relation to the body, the radiator support mounts are 3" further back on the frame rails. I pulled a tape on it in a few spots yesterday while I was taking out the cab bolts on the 71, and off the top of my head they are as follows, with 71 numbers first:
Bed bolt width, 31" vs 34"
Radiator support from kingpin, 21" vs 24"
Radiator support width, 31" vs ~40".

The rough profiles of both frames are about the same, I will have to add a crossmember under the cab for the 71 mounts, in the end it'll have six cab mounts as the extension will have it's own too.
Right now the shop I am working at is moving, the trucks are at the new location but the lifts aren't in yet. I will be pulling the cab off once a lift is set up, so I can get solid locations on the mounts for it. Due to the midships fuel tank, I can't pull the bed until I drop that tank, or pull the cab so I can reach in and get to the front bed bolt.
I am going to thoroughly document the differences between these frames and hopefully that will help some people in the future.

 

NICE BUILD,KEEP THE PICS COMEING.

 

Interesting...i need to watch this!

 

I beg to differ sir. The 4 in is welded under the existing floor pan, and the widening takes place behind the rear cab mount.


John

 

The rear axle that was under my old build was from a 68 F250 that was put onto a 79 F350 4x4 chassis. The guy said it dropped right on, and I am inclined to believe that. I know the rear frame with did change, but have seen nothing about the body mounts changing.

 

This looks pretty good. I'll be interested in seeing how it goes.
What part of Oregon are you in?

 

That's going to be a interesting build. I have always liked twist.

 

Count me in, anxiously awaiting updates!

 

Today's fun:

Because of the auxiliary fuel tank, I couldn't get to the front bed bolt on the driver's side, so the cab had to come off first. I just got the lift bolted down today and it needed a test anyways.