4 door B tow pig.

I had a local auto glass shop cut some for me before and it took about 10 min and 20 $ because I had the glass..

But that was 10 years ago. . I guess I'll find out when I'm at that point

Like the idea... I had thought about this concept for other vehicles... stretching that is... Will be following your thread to see how it turns out!

You won't be able to cut tempered glass. Other solutions are get some factory back glass from Australia or other country where those were sold, get a back glass from something similar or use plexi.

I am going with a similar one. I got glass from the rear doors of a first gen Mazda MPV van. They were almost square, about the right width and 100% the same curve. That is the most important. I took a stock B glass and laid it on it's end and traced the curve. Then I took it to the wrecking yard and matched it. I figured Mazdas from that same era would be the same. They are the same curve and also the same mounting holes. Plus the MPV power regulators match the B door. So now that I have glass I will have to make the doors in reverse order. That is make the the doors fit the glass. Then whatever length they turn out to be is the length of the rear doors. It should be longer than a 4 door B but shorter than a B front door.

Here is a pic of the one I did in the 80s and 90s. Stretched it twice. This time I need both doors to have one seam. It can be done with stock sheet metal. But the rear doors have to be made around the glass size first. Then I can add the rear door frames to the reg cab. I also planned to use an ex cab for the back of the crew cab so I have the smooth cab corners. About to start cutting on it very soon. I also have the roadster project I am working on.

I also got a long bed out of a wrecking yard to use on this project. I bought an ex cab bed also so I should have plenty of extra Mazda sheet metal. More to come.

Here is a pic of my kid's shop with all 6 of my trucks in one pic. The two gray ones are work trucks. The rest are projects and parts trucks. Gotta use one cab front for the roadster and one for the crew cab. Right now the plan is to tear them all down and organize the shop so I can work on both projects at once.

Today I have a little spare time so I am going to cut the skin off of a spare door and get the rear door glass I got and do some test fitting to see what I will have to do to get the rear door glass to work. Pics soon.

So yesterday I decided to cut into a spare door to test fit my new rear door glass. I knew I would need to move the window track and modify the top of it to fit properly. I cut the door skin off this door and laid the new glass in to see how well it fits. The good thing is that it is only about 3/8" wider than the stock glass. That means I will only have to move the track over that much to fit. I will not have to cut the door down to a shorter door. That will help with the overall look as the factory 4 doors have a very short rear door. There must be very little room in the back seat of those trucks. I should be able to run a regular bench seat in the back. Here are a few pics of the test fit of the glass. I laid a new rear door glass over a stock Mazda door glass. Pretty close in width but quite a bit taller. If I cant get it to roll all the way down I may have to find a different rear door glass. Thus the reason I was test fitting this now. I have to have a for sure solution on the rear door glass before starting the process of building the cab. And the cab has to be built before the frame as the cab length is not set in stone until I know the rear door length.

I have already started researching this, because I've been planning to do the same thing for over a year now. It seems you're moving forward a bit faster than I am.
I purchased a rear door glass from a late model Chrysler minivan. Some of them have windows in the sliding doors that roll all the way down, AND they're available with factory tinted glass. The thickness is the same, and the curve is real close too. The only issues I can see, is the need to modify how the regulator fits to the glass, or modifying a Chrysler regulator to fit the door. And the width of the window, but you already planned to widen the window track.
I'll put up a pic as soon as I can.

Sounds good. I would love to see pics. I went to the wrecking yard with a template of the curve and several were exact same curve or similar. But getting square door glass is much more of a pain to find. The ones I have were first gen Mazda MPV from the rear. If I can't get them to roll all the way down I may have to look some more.

This is my secondary project so I don't have to get it done soon. Can't work on the first project until I get a second welder to take down to the shop. So I figured I would do some problem solving on this. As you might guess this is just one problem of several that have to be overcome to successfully build a crew cab without it looking goofy.

The other problems are:

1. Cab taper. It tapers at the front in and down. So the doors and door frames have to be cut to make them level or parallel with the bottom of the doors.
2. Cab narrows at the front. So the easiest way to solve this is to cut the entire door frame out of the side right past the pinch weld and then graft it on.
3. Doors edges curved. The rear of the front doors and the front of the rear doors need to meet. Like any 4 door car the seam must be straight.
4. Roof. Nuff said there. Likely going to have to find a minivan or SUV roof that is close in shape and length. I would even go for one with ribs.
5. Floor. No problem. I have solved this one before and it should be no different.
6. Frame. Again no problem. Since this one will not be a full custom show truck I will use factory frame parts to make this possible.
7. Driveline/lines/hoses/wires. I solved these issues building the limo stretching it twice. The least of my worries.

More to come. I welcome any discussion on this.