trailing arm perch relocation

[scum1]

Thanks for the response,

I'm trying to imitate various setups that have the upper bag plate welded to a boxed section of the inside of the frame, just before the rear axle, and the bottom plate welded to the trailing arm. To achieve that correct angle and distance away from the frame, the trailing arm perch and u bolt would fall right under my notch (which is not wide, or long enough) and would make contact with the perch.

I could however, make a shackle type mount under the axle in the correct location, eliminating the need for perches and u bolts, and have a bushing end on the trailing arm attach to that. What would be the difference between having a "fixed end" via trailing arm perch with u bolt, vs a "fixed end" via a bushing attached to a shackle. I hope that makes sense. I'm not familiar with all the correct terminology.