Flatbed mounting brackets, will these work?

[ObnoxiousFumes]

It’s amazing how little information Google will find for this sort of thing.
I am putting a flatbed on my Dodge, and I have four out of the six brackets figured out so far. I thought I had a plan for the front two but now I’m second guessing it. I was thinking I’d weld these angle pieces to the flatbed frame, utilizing the old box mount but I thought I should ask you smart people who know about building things.
How would you guys do this?

 

[jack stand]

That should be fine but I'd either run it all the way across notching the long sills or do as you have pictured but add a similar six-member in between the long sills.

 

[Spareparts]

Are you going to do the 2 on the pictured side and also on the other side, that should be plenty

 

[Rusted Nut]

I just built a flatbed for my F 350. I bolted (3/8” Grade 8) 4” pieces of 3x3x1/4” into stock bed mounting holes on the truck frame rails, and welded the flatbed frame the the blocks.

 

[36truck]

If your a good welder or know someone who is that should be fine with the 4 of them. What are you doing on the back end. Is it sitting on the frame somewhere?

 

[ObnoxiousFumes]

Are you going to do the 2 on the pictured side and also on the other side, that should be plenty

Yes those two in that pic, and one more at the back that is not pictured, then the same on the other side. Six mounting points total.

If your a good welder or know someone who is that should be fine with the 4 of them. What are you doing on the back end. Is it sitting on the frame somewhere?

It rests on the frame pretty much from above the axle right to the back, the frame only drops down at the front (pictured).
I might weld it myself, or just tack it and get a welder buddy to weld it, we’ll see how my practice runs go.

 

[ObnoxiousFumes]

I just built a flatbed for my F 350. I bolted (3/8” Grade 8) 4” pieces of 3x3x1/4” into stock bed mounting holes on the truck frame rails, and welded the flatbed frame the the blocks.

That’s cool, I wanted to build my own too and make it just the way I wanted it, but I eventually had to face the fact that I’d never get it finished...

 

[i4ni]

I just built a flatbed for my F 350. I bolted (3/8” Grade 8) 4” pieces of 3x3x1/4” into stock bed mounting holes on the truck frame rails, and welded the flatbed frame the the blocks.

i assume tires clear the frame. Hard to tell from the pics. Nice work