Steve, that would be me using the GM Metric part (G-body and S-series) - I emailed you some information as well as replied to your post....
I believed you now answered how the idler was located. As you found out, it only takes a minor shift in alignment to make things caddywhompous
I think That Steve (OldSub) is looking to keep some beefy suspension under his truck for hauling without doing a frame swap or front clip swap.
