To change from a single to a double cardan setup at the transfer case you may also need to change the yoke. I've seen it done with the same yoke, but with some models at least they seem to be different. Might be the difference between 1310 and 1330 series setups, but no real idea. Just something to check. The double-cardan/CV setup uses four bolts to hold the shaft to the yoke, vs the two u-bolts with nuts holding a single cardan.

You might also run into another issue. With 4" of lift AND 7 degree C-bushings AND aftermarket arms, your caster might be good, but your front pinion yoke might be pointed down at a pretty steep angle from the centerline of the driveshaft. You're changing all the angles, so need to make sure they continue to work together the way they should.
With a standard single-cardan shaft your angles (front pinion shaft and t-case output shaft) need to be near the same at both ends of the shaft. With a double-cardan shaft the front pinion angle is best pointed up to near the center line of the driveshaft. Look at your rear driveshaft and you'll see how this relationship works. After the lift is installed you might have to modify the rear pinion angle as well. But you won't know until you get it all put together.

The front can get away with a lot more angle disparity than the rear, but there's still a limit even with a double-cardan. Like you found with your existing shaft.
Just for the heck of it, do you have a picture of the driveshaft and front pinion relationship?

Thanks

Paul

 

thanks for the info Paul. I finished installing the lift, here are some photos. The front pinion looks to be level or slightly upward. Rear angles look good. I drove it without the front drive shaft and it drives way better
than before the lift. The caster is now positive. My main problem with the lift is the amount of rake. The rear is about 2.5 inches higher than the front. I hope it settles in, otherwise I am thinking of removing my stock axle blocks and replacing with the Bronco wedges from JBG.

 

Test drove it today, drives better than it ever has since I owned it. Amazing what some camber will do. The rake isn’t as bad as I thought. Here is a picture on flat ground. Now I need to get an alignment and I’ll be back on the road.

 

Great looking truck! Unusual color, but very nice. Complements the Ford lines very well.
Yes, a 2.5" rake would be excessive for a lift spring. Close to a stock rake maybe, but most aftermarket springs for full-size trucks don't that big.
Our 10 and 11 leaf packs for Broncos definitely need time to settle down and do sit high at first. Especially with an empty Bronco like going without the top or spare tire or back seat. In those cases it's either force the compression to accelerate the settling down, or if you don't need the extra capacity just remove a leaf or two.
Yours looks barely up in the back. The way to tell is to put a digital level on the bed rail, then compress the suspension until it's either level, or until you like the look. Measure the before and after from a convenient spot, and that's the amount of change you want. For just a little bit like yours, the springs "might" settle out.
Then again, an empty pickup bed isn't exactly going to stress out those springs. So you may have to help things along.

To the driveshafts, your rear looks practically perfect. The correct alignment for u-joints in a double-cardan setup is to have the rear pinion pointed basically up into the centerline of the driveshaft. We've found that 1 or 2 degrees down from that centerline works well for vehicles that have lots of axle-wrap during accel/decel motions. Otherwise a zero degree angle can work pretty well too.

For a single-cardan shaft, the u-joints have to be co-equal in angle. Meaning that if the transfer case output shaft is, for example, 5° down from level (compared to the ground) then your front axle pinion shaft needs to be 5° up from the ground. NOT up from the shaft centerline, but compared to the ground the truck is sitting on so that the two basically cancel each other out with the shaft in-between.
The variance should be within just a couple of degrees of each other to avoid vibrations and excessive wear. There is also an overall angle limitation dictated by the shaft and joints themselves. As you've already afoul of.
I forget the angle limits for each size u-joint, but it's written down somewhere.

With a double-cardan shaft in the front, you may not run into the overall limitation (though you still might) but you will likely still run into a vibration in 4wd high-range if you can't point the front pinion to within a few degrees of the centerline of the driveshaft. The more caster you add to your front end, the more likely you are to run into trouble with a double-cardan shaft.

In case you were not aware of the "cut-n-turn" method, really the only way to correct for both caster AND the pinion angle is to set the pinion angle using C-bushings and set the caster by grinding off the weld at the outer steering yokes (often called the "inner-C's") and rotate them on the end of the axle tubes until you get the caster number you want.
It's more hassle and expense, but it's worth it if you want to have your cake and eat it too.

As you're finding out, lifting a truck is not always quite as easy as just installing new springs. Sometimes you have to cobble things together first, mock up new component changes, then make them permanent once you've achieved a balance in the force.
So keep in mind what all you'll have to do to correct a pinion angle and keep good caster numbers, depending on which driveshaft type will suit your needs best.

Paul

 

always an option,
https://4xshaft.com/products/super-flex-universal-joint

I had good luck with one at pinion that liked to bind in the front of 79 f250 with 44's under throttle in 4x4.
1350 double cardan shaft up at t-case and superjoint 1350 at diff.