I installed the Air Lift 60786 Universal Kit. It's not the perfect solution (it probably needs to be a bit taller), but it does fit. I could only gain back 1" of the over 3" of sag with the air bags at 35 psi (nmax pressure)
So far I've only driven with the weight distribution hitch and the air bags, not the air bags alone.
The result (trailer is approx 8,000lbs with 1,050lbs on the hitch)
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Keep in mind that I'm just a weekend warrior, doing what makes sense to me. There are plenty of generic air bag install videos on YouTube by more skilled / experienced mechanics than me.
Install was pretty easy. Jacked the rear, put jack stands under the frame and chocked the front wheels, disconnected the panhard bar, sway bar and shocks and lowered the rear axle as much as possible without
putting strain on the brake hoses. It would be possible to damage your brake lines if you weren't paying attention.
Removed the upper bump stops (just popped them out by grabbing them and pulling down).
I also lowered the spare tire as it is really close to the back bumper, making access difficult, and for where I put the fill-valves, it was important not to drill into the spare tire.
The failure modes I've seen for these kits involved bags splitting, and air lines kinking and failing. I was carefull not to stress the bags themselves by clamping them flat or folding them like a hot dog bun - there was no need. Anywhere the air lines would be in contact with anything including the zip ties, I put clear 3/8" OD / 1/4" ID vinyl tubing over the air lines. Where I went through the frame above the rear coil springs, I put a 2nd layer of clear tubing over the first layer. To slide the clear tubing on, I used a few drops of tire mounting lube poured into the clear vinyl tubing.
I de-burred the hole in the top spacer with a stepped uni-bit.
I lightly folded the airbags by hand and slipped them into the coils with the nipple pointed up. At first I didn't have the protective clear tubing on the air lines, so when I re-did the connection after sliding on the tubing, I clipped off the part of the air line that had already been forced over the nipple on the air bag - I didn't want to use clamps in that location, and wanted the tightest seal possible between the tubing and the nipple.
I routed the air lines along the electrical harnesses, across the back bumper and installed dual schreader valves so that air wouldn't transfer side to side during cornering.
I decided that I wanted the shraeder valves really easy to access, to I used the two bottom holes in the license plate (tag). Because the valves are half in / half out of the plastic support, I made an MDF drilling template, bolted it in place with the top license plate bolts, and starting with a 1/8" diameter drill, stepped up the hole size in three steps.
One thing to note with this location is the spare tire is too close. A 90 degree bulkhead fitting would be ideal here, but I have yet to source one. If anyone knows of a supplier for a shraeder valve bulkhead fitting with a 90 degree barbed connector for 1/4" air hose, please share the info. As an interim measure, I again slid clear vinyl tubing over the air line to help reduce the chance of kinking and failure at the fill valve... it's only a matter of time.
Air bag in place:
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threading the tubing into the hole above the air bag
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Coming out through the top of the frame - double clear vinyl tubing protection
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License plate mounting frame. The screws just go into the plastic (no inserts), so don't over-torque them
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Simple drilling template
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Clear tubing protection and clamps on the tubing where it meets the fill valves
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Dual fill valves:
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Might as well get some practice lowering the spare
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This is what you're aiming for:
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Torque your wheels... according to the PDF manual:
Steel wheel: 154 ft•lbf (209 N•m, 21.3 kgf•m)
Aluminum wheel: 97 ft•lbf (131 N•m, 13.4 kgf•m)
I hope this helps somebody else figure out what they want to do on their truck.