Top mount for rear airsprings (trailing arm)
 

I'm mocking things up and I see that my bags center up in the frame (and c-notch re-enforcing plate!) real well, which is more likely attributable to Nathan Porter having made the trailing arms correctly than anthing I did.. lol

What I want to check before I move on is if I need a mounting plate on top. The bags are wider than the frame section. They frame section is very heavy here (thanks to the notch plate) so I'm not worried about it buckeling but I thought I should ask y'all if it's ok to simply bolt (and plumb) them through the frame or if I should make a plate (w/wo gussets?) that covers the entire width of the bag.

Re: Top mount for rear airsprings (trailing arm)
 

No need for the full diameter plate. There's enough material to support the weight as is.

Re: Top mount for rear airsprings (trailing arm)
 

Cool.. thanks. :)

Guess I need to doing some drilling and reaming and then get to cleaning up the third member. (It needs new seals and I'm going to take the opportunity to replace the shoes while it's out of the truck and easy to get to since that is such a pita with the HO52 rear end.