So I have a possible complete donor 1999 F250 7.3 with a 4R100 transmission that I would love to see in my 1975 F250 Highboy Frame. I was watching some videos and what they were saying is that because of width of my frame it would be extremely hard and a butt load of Fabrication to get it to adapt to my Frame. What I don't understand is how that could be when I could put a 460 in that frame and physically they are very close to the same size except for the hight of the engine where the 7.3 is 6 inches taller than a 460. The pan drops in the back of the cross member on the 7.3 so that should work for my application on my 75 Frame. Has anyone done this and am I being fed a lot of Crap about how hard it would be to adapt the 7.3 to this frame? I was also told that the 7.3 would bolt right up to 460 Engine Mount Towers. Can anyone shed some light on this or guide me to someone who has done it and would be willing to share the information on how to do this? Thanks For any Help you can give with this.

I am planning on using my 1971 F100 Body on this so this is really turning into a Frankentruck Project.

 

I built a 49 short box chev show truck on a 73 blazer frame. Had to do my share of making everything work, but what a beauty.


Can be done. As far as specifics, break out the tape and go to town. Easy!

Don't cheap out on body mount stubs. They'll get ya.

Denny

 

What do you mean Body Mount Stubs? Do you mean a body Lift?

 

I'm going to guess that Denny means the outriggers welded to the web of the frame that hold the body mount pucks.

I don't remember which year Ford transitioned from narrow frames (34") to wide frames (37"), but it happened right smack in the middle of the years you are working with... mid 1970's.

Even the post 1999 F-450 and F-550 chassis cabs, which are narrow frame (34") trucks on the business/bed end, are actually wide frame (37") at the engine end. Their transition from wide frame to narrow frame occurs underneath the cab.

You seem to have answered your own question regarding the similarities and differences between the 460 gas and the 444 diesel. If both have the same net width, but the 444 is taller, and both blocks are in a V shape, then the width can still vary between the engines at a common point in height (say, at the motor mounts) and therefore create issues when trying to maintain a driveline angle to the transmission and still be able to close the hood.

Notwithstanding, what you are trying to do has been done. On this forum, the very best example I've seen was done by FTE member Cleatus12r, with an utterly stunning light blue 1973 7.3L. Imagine that... a '73 7.3. That was not be accident. Then again, Cleatus12r can stuff a 7.3L Powerstroke into a late model Crown Victoria sedan. Literally. I'm not kidding. And it runs. Search his posts. He KNOWS about 7.3Ls, and has personal experience fabricating vehicles to fit them.

 

Spot on brother.

Measure wheel base to make sure your fenders aren't pooched and drop the cab and box on it and you'll see what I'm trying to explain. Simple Math, but if you want it to look right, you have a lil measuring and fabbing to do.

In my case, I chose the blazer frame because it was about 3 inches off center for original bed, front to back. 4 inch offset side to side. I set up the cab and made the peds to adjust for height , the older trucks were very low for cab clearance. I then went after the bed, I wanted custom, not stock, so I fabbed the bed out of diamond plate alum and had it bent and welded by palmer shipbuilding in sturgeon bay, wi. That way I could put the fiberglass fenders where they looked stock. Won alot of shows, but after my daughters used it for a bicycle rack in the garage against my see you from across the street high gloss black paint job I tired of it. Didn't need to yell at the kids or repaint the truck anymore. Happy family, sad Dad.

I'll dig up pictures, you'll understand.

Denny

 

Your frame is the narrower frame mentioned above. The transition to wide frame was in 77.5 which is when the "highboy" was put to rest. I'll say this: I've seen a build thread on the internet somewhere where a guy did this swap. I can't say for sure what frame he was working with though. In fact if memory serves correctly, he swapped most of the interior in as well. That being said, it was a ton of fab work. I'll see if I can dig it up.

 

https://jonesys.com/1979-f350-ford-7...e-engine-swap/ < but it's into a wider framed 79... I looked all over for you and couldn't find it. There's tons of Cummins swaps into all different years throughout the 70s easily accessible with a google search, but I have a specific truck in mind and I can't find it. I couldn't say for sure that it wouldn't be in the wider frame anyhow.

 

Funny you mention the Cummins Swap, I have decided on a 4BT but the newer one that is about 170 Hp and 300 Ft Lbs of Torque. The one I found has an Allison T1000 hooked to it. I plan on putting in a P Pump and a S200 Turbo upgrade and this should put the HP up at about 300 RWHP and the Torque at about 500+ Ft Lbs of Torque. I think this will be plenty of HP and Torque for the Truck I am going to be running with the Tires and Gear Ratio I have. Its taken me a bit to figure out what I really wanted but I Appreciate the footwork you did for me in regards to the 7.3 Option. I think its a little above my Paygrade to install the 7.3. Either way I think this is going to be one amazing Project and should be driving down the Road for a long time and able to pull just about anything I would ever want to pull with the truck.

 

Hate to be off subject. But is that a 66 mustang beside black truck.
just wandering. My dad bought me one for my 15th birthday in 1985 .and I still have it.

 

Its a 67 Mustang and its close to being finished. Its my Wifes Mustang and she has had her hands on just about every aspect of the Build.

 

That's cool she's working on it herself.
my dad and I rebuilt the motor and transmission in mine in 1986 . And I had it painted red . Witch I regret.
I'd like to repaint it the original yellow on day.
Mine came with 200 Sprint 6 cylinder.
Auto trans. Power steering and breaks.
And a factory under dash mustang a/c
When my kids get out of the house I'd like to re do it with a small v8 . Something reliable the wife and I could take a road trip in.

 

Father and Son Projects are cool. Im thinking that I would like to get Myself, My Son and My Grandson a Project we could work on and one day give it to my Grandson. I thing Give is the Wrong word, if he wants it he will have to spend lots of hours working on it.

 

I been reading a lot of post about the subject of putting a 7.3 in a 75 F250 highboy 4x4. A lot of people like me want in site or help on the subject. But it seems like everyone who chimes in on subject. Always say something that doesn't have to much to do with putting that engine in a 1975 chassis. They change it they modified older to body to fit a newer chassis. In reality that changes whatever body you use to the year of the chassis you used. Because the pink slip follows chassis not body in all state. So in reality it is not a old school

 

It's been a while since this thread was active, but I will interject as I'm one who did it the "not old school" way. I'll preface it by saying that nearly all states allow the different body/frame mismatch SO LONG AS ALL the required documentation and inspections are done.

Now that the legal stuff's out of the way, the reason to not just slap a 7.3L into an old chassis can be explained in one sentence:

The drivetrain and frame are not heavy-duty enough to withstand the forces the 7.3L are able to put on them if you actually plan to use the pickup for anything pickup-esque.


The "highboy" is junk. A mix of 1310 and 1330 u-joints throughout the thing, drum brakes on the D44 front axle (better on the 75-76 disc brake versions) and the really weak u-joints in the closed-knuckle versions. Using the later frame and drivetrain allows full GVWR and GCWR of the later vehicle because EVERYTHING is beefier and makes the pickup stylish as well as useful.

 

I'm only using the chassis and 205 transfer case. I have a 1978 open knuckle front end completely rebuilt with yukon parts. And 2016 Sterling 10.5 with electric locker in the rear and rebuilt and enforce drive lines. With all 4" lift big bloc skyjackers suspension. Oh yea, as soon as i figure out what i have to do about the motor the chassis getting boxed in. I just wanted to know how much fabrication i would have to do before I start. But no one on here like to stay on subject. So people can get answers that might help others in the future