Dimensions for converting rear from leaf to coil

[steinepstein]

I'm converting my 68 GMC from leaf to a trailing arm setup....

Does anyone have trailing arm perch dimensions? Those perches are welded on at an angle and are set at some distance from center. I'd love to get those dimensions, any help would be appreciated.

I realize that I could take the truck to a chassis shop and they could line everything up straight and square and weld it all up, but I'm not at that point yet and don't really want to haul it all over there either.

If I am going about this wrong, please let me know, thank you.