Gary, did you happen to weigh these, or know how much lighter, if any, they are?July 2013 update
I have a set of Tubular Trailing Arms in to build. These are pretty nice, I guess there was an issue with brackets in the past and that is corrected. They come with "johnny joints" in place of the stock rubber bushings. I can't say I've had any problem with good rubber bushings for the past 40 years.
They come with larger 7/16 bolts they use over the original 3/8 kurled studs that are used in the stock and offset arms.
The arm holes are drilled oversize so the bolts are loose fit, the caliper bracket holes have to be drilled larger as well since they are 3/8". Once it's all torqued up it should be ok but I like the stud better.
With that said I'll leave it up to you if you think these are what you want. They look super great & are strong but I have never had a stock or offset arm fail - unless it was impacted and/or rotted. I have new stock arms on my street vette and my son's drag vette and they work fine.
Here are the supplied grade 8 bolts and locknuts
Front bushing. I use stock rubber in all my cars and like them. I haven't tried these in one of my cars.
Bolts won't go through a 3/8 hole, make sure you want to drill your originals out otherwise get another set of brackets.
Supports may need to be reemed too
Pretty loose in the arm, I don't like this part at all.