51,
Did a simple version that should apply for your truck. I only neede a little bit to squeeze in my new tires and didn't want to go and but expensive peices so I made my own. Have a gallery showing how i did it. mine cost ne about 5bucks for both sides. Good Luck

 

Yes, that would be the easiest way to do it. I'd cut them off with a fine metalcutting blade on a variable speed reciprocating saw as close as possible to the bed wall if I was doing it, that way you would only have one flat weld to deal with. True up the edges with a sanding disk so you have a straight edge to butt against. Cut both sides and true the edges to the same dimension before you have the filler piece sheared in case one side cut wobbles more than the other side you can true them both to the same width and then the width will come out the same on both sides. Turning the bed upside down and weld from the bottom will make cleanup a lot easier if you don't have a lot of bodywork experience. Have a strip of cold rolled sheet (steel silver surface color) sheared to the width you need with extra length. leave it a little long on the ends and trim it after welding. Use hot rolled steel (black surface color) as a second choice if you can't find cold rolled, but you will need to sand off the black surface along the edges where you are welding.
clamp the inner portion solidly in place and keep it clamped while welding to keep everything from warping all out of place. I'd weld the bed side edge first, adjusting the shape and fit to the inner piece then weld the flat seam. Keep your welds short, < 1/2" and spaced at least 12" apart, start in the center and work towards both ends. allowing each to cool to room temp before adding another. When welding the flat seam grind the bead near flat and readjust the fit between beads with hammer and dolly as necessary as you go. Don't leave warps and misfits unadjusted until all the welding is done, it will be very hard to fix them after you have locked them in place with weld. DON'T get in a hurry and try to rush the job, or you'll end up with a mess on your hands. It took me a full day to weld in each taillight bucket on Gracie, a seam < 1/2 the length of each one you'll be dealing with. Work back and forth from one wheel well to the other while waiting for the welds to cool.

 

Nathan,

Have you considered taking the wheel wells from a late model wide bed truck bed and welding them to your bedsides? When I aquired my donor bed for my project my buddy had cut the bed sides off for me and left me with a bed floor, the bed front, and both wheel wells. I further cut the bedfloor down to fit my application which left me with two good fender wells. I intend to use them for a utility trailer I'm putting together.

you could probably get a set from the scrap pile at a local body shop or fairly cheap from a wrecking yard

Just something to think about
Bobby

 

Great idea Bobby. About the same distance to weld, but only one arch up and over to weld, instead of two along both sides of the 3 inch strip. The remainer is all along the bottom in straight lines. Easier is better sometimes. Of course the hunt is a great part of the process. Have a great day,chuck

 

Ax,
So I'm supposed to cut the wheel tubs flush with the bedside? I do have a plasma cutter available. That would probably be more accurate than using my reciprocating saw (which my Dad currently has borrowed ). So I would have to use a small square to keep the addition perpendicular to the bedside? How would you clamp a 90 degree angle?

Bobby,
I haven't found any later wheelwells that look good and they are all too short. Most I've measured are like 37" long so I would have a 2" gap on either side to fill in.

 

Nathan,

I didn't think about that, but you're right. I just went out and measured the ones I have, they are only 36".

Good luck with widening yours
Bobby

 

Plasma cutter would work. The filler strip will support itself once bent to shape. I'd clamp the inner portion the correct distance away from the wall, likely using something like a piece of angle iron maybe under and clamped to the floor flange? Then clamp the prebent filler strip in place in between. If the center wants to droop, I might try a welders magnet underneath to hold it up flush until you can put the first tack in place in the center (remember the bed is upside down at this point so you can stick the magnet to the bedside where it will hold the strip perfectly perpendicular. ) move or use additional magnets to hold the metal flush as you continue to add tacks ~12" apart working alternately out from the center. The inner section is there only as a guide to maintain the shape until the strip is fully welded to the bedside. grind your welds smooth if you want, or since the bead will be hidden by the outer fender you can just leave it or knock off any lumps or high spots.
Now readjust the shape of the strip to the inner piece and begin attaching it to the strip again starting at the center and working outwards. You may (likely) need to do a little on dolly stretching to correct the heat shrinkage along the flat seam as you start adding tacks between the first set. Correct as you go to minimize a more difficult job flattening it later.

AFA wider donor wells (trailer fender or from later pickup) being too short, I think you aren't looking at the at the job from the right perspective. You could split the donor piece into front and rear 1/2s and extend them with a strip down the center at right angles to the bed. That would actually be the easier job. I'd attach the 1/2s to the bed wall before adding the filler strip, again tacking or clamping a support between the 1/2s in the area that will end up under the bed floor.

 

Just I want the truck to look stock and later wheelwells to me just don't fit. 67-72 ones are trapezoid shaped with ribs and 73-96 wheel tubs are molded into bedsides. They also have the middle stake pocket rib.

I also don't have any fancy metal working tools so I can't make a rounded 90 degree corner to extend the later wheel tubs.

I like this idea the best.

Where I just weld my 51 wheel tubs onto the 53 ones. They have exactly the same curvature and size.

 

Go get them Nathan, I used my welder first time today. I need lots of practice. I will let my friend help me so I can finish this year.

 

Well, there you go! My only question is the smaller wheel well going to provide the clearance you need for the size tire you are running? remember the wheel not only moves up and down but tips in and out as well. That's usually the reason for tubbing wheel wells straight in rather than tapered as in your sketch.
What kind of fancy tools do you need? My fanciest tools are a shrinker and stretcher, otherwise I do most of my forming over wood bucks, hammers and dollies or with a plastic torpedo mallet and shot bag. There isn't much of anything a fancy machine can do that isn't possible to do with hand tools and a little more time.

 

I got lots of side and top clearance. Here's a picture showing where the wheel tub is approximately. The flat line is the bottom of the wood floor.

 

how much space is there between the wheel well and the frame? The wheel wells on my 56 Panel are right against the frame. Tubbing would gain me nothing unless I narrowed the frame as well.

 

I still got lots of room and the wheel tub sits on top of the wood floor also.

 

If the newer tubs are too short you could easily cut cross ways and add a strip down the centre to lenghten.