My links are all 7075 Alum... using 2" for the lowers, and 1.75" for the uppers.. Joints are the Currie forged Johnny Joints with a 1" shank on the uppers and 1.25" shank lowers.
I went with Aluminum because:
1: It's significantly stronger than 2" .500" DOM
----- 2" 7075 AL link in my length takes 6800lbs to bend permanently, weighs 11lbs.
----- 2" .250" DOM link in my length takes 3200lbs to bend permanently, weighs 13lbs.
----- 2" .500" DOM link in my length takes 4350lbs to bend permanently, weighs 22.5lbs.
----- 2" .250" 4130 CroMo link in my length takes 4000lbs to bend permanently, weighs 11lbs.
----- 2" .500" 4130 CroMo link in my length takes 5500lbs to bend permanently, weighs 22.5lbs.
2: I was trying to save weight where I could without sacrificing strength and longevity (How many 2-seater 4WS rockwell rigs have you seen that weigh 4600?) I saved ~80 lbs in link material alone.
3: It wasn't THAT much more in the end than DOM + inserts, and was less than 2" .500 CroMo (Which I would have drilled and tapped)
4: No weld to fail. (minor reason)
I have landed directly on the links several times (Can Opener at Harlan is a prime example) and you feel it give ever so slightly, makes the landing a little nicer. The difference is, when steel bends, it tends to stay bent. Aluminum is easier to bend, but comes right back to shape, which is why 7075 is what the landing skids on a Huey are made from...
If you get AL links, do NOT taper the ends, keeping them full diameter gives the jam nut a good surface to grab onto, and keeps the wall thickness good around the threads.
Just my $.02..
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Rich Q.
5.3 powered FJ-buggy thing on rockwells & 42's, with a throttle happy driver.