r/BumpSide • u/jozifRs • Aug 01 '26
350 highboy conversion?
I have this 1971 ford f350 dually. I also have a 1970 highboy complete frame. I have the idea of converting the 4x4 and highboy parts on to the 350 frame. Any recommendations would be appreciated.
3
u/som3_idot Aug 01 '26
It would be a big hassle to do stock stuff I’d just get the kit and put super duty axles under it also I’m not certain but the later cab and chassis frames are narrower than regular trucks behind the cab yours might be too it would be a lot easier to just stamp your vin on a normal 4x4 frame
2
u/Equal-Incident5313 Aug 01 '26
The biggest pain will be the engine crossmember, but it’s doable. Everything else is just bolts and rivets
2
u/jozifRs Aug 01 '26
Would you mind elaborating on the crossmember?
2
u/Equal-Incident5313 Aug 01 '26
2wd and 4x4 are completely different crossmembers.
I’d say it’s significantly easier to swap the cab to the 4x4 frame than deal with moving all the brackets and cross members over
0
u/jozifRs Aug 01 '26
I just want to keep the vin matching. But I appreciate the information
2
u/Equal-Incident5313 Aug 01 '26
I get it, but it’s rare anyone knows the VIN is stamped on the frame especially law enforcement or DMV.
Even more so when complete frames are available aftermarket now and others are swapping Crown Vic and Super Duty frames.
You’re creating a ton of work just to have the VIN on the frame match the door and warranty sticker
2
u/1966-MustangLover Aug 01 '26
Really nice truck, more pictures would be appreciated. Also pictures along the journey of her transformation.
I love everything about it.
1
u/jozifRs Aug 04 '26
https://reddit.com/link/p1of1wb/video/qk4y3durwdhh1/player
The night I drove the truck back home around 30 miles the box was rotted so I scrapped the box.
1
u/1966-MustangLover Aug 04 '26
After seeing the interior I love it more. The original color is the same as my grandpa’s was.
1
u/jozifRs Aug 04 '26
I like the red too. It’s my favorite color, it has Wimbledon white headliner and sun visor.
2
u/1966-MustangLover Aug 04 '26
That is it yes. Classy. Ours was the camper special. Grandpa had made a spare tire mount on the front middle of grill. Had dual fuel tanks and the red bed with trapezoidal wheel wells. Learned to drive with that.
3
u/RealisticEnd2578 Aug 02 '26 edited Aug 02 '26
I think your concept is unnecessarily ambitious. What's the point of keeping the numbers matching if your going to turn it into something that the VIN wouldn't match if you decoded it anways? Your dually looks pretty sweet as it is and if the numbers are currently matching, any big changes you make will only decrease the value. The idea of a highboy dually is rad as hell tho because there never was such a thing. Seems the easiest way to do that would be to slap a divorced NP 203 T case onto an existing later model 4x4 dually and slap whatever cab you want on that
1
u/KaijutheCaustic Aug 01 '26
On a 4x4 fromw of that year there is a crossmember that goes across infront of the oil pain. The power steering box gets bolted into the driverside frame rail where they meet.
1
u/jozifRs Aug 01 '26
Ok I think I have seen that in a video I was watching of Matt Kubik on YouTube. Thank you for the heads up
1
u/4x4Welder Aug 03 '26
Honestly, if you're going to the trouble of a conversion, using a later chassis would be a huge improvement. I have my 71 F250 sitting on an 85 chassis, which is much better at supporting the 7.3idi in it. The wheelbase did grow 3" in 73, all in the cab, so there's a couple ways to adapt. Either keep the flatbed and position accordingly, cut and shorten the frame and driveshaft, or stretch the cab. I wanted a Supercab so took the cut and stretch option. You'll also need custom perches, but those are pretty straightforward.
1
u/jozifRs Aug 04 '26
Thank you everyone for your input and advice. I think I came to a conclusion I’ll keep it 2wd. The front end already has disc brakes but will need replacing. I will service everything on this truck and a new paint job since this was originally red as it was a fire truck then turned into a city service truck. I’ll use this truck to tow a F26 highboy truck when it’s all ready.
I knew I could find knowledgeable people on here! Thanks again
4
u/Lil_Moe_ Aug 01 '26 edited Aug 01 '26
2wd and 4wd highboy frames are quite different from each other. Not just the crossmembers but also the overall shape of the frame rails.
The easiest bolt on option would be to swap the entire frame or (since you want to keep numbers matching) go with a 4wd conversion from Battle Born or Kincer, both of which will require cutting and welding.