another newbie with a question

[E's69GMC]

I've been reading this board for about a month, and joined last week. I wanted to say Hi and say that you all have some nice trucks and projects going!

I have a 69 GMC C2500 of my own that I have been working on for the past two weeks to get it on the road, this will be my daily driver AND project. I want to switch it from leaf spring rear setup to the trailing arm setup, I have the arms, shock crossmember, and panhard bar mount. My question is, has anyone on this board done this before? And if so, how do I go about locating the shock crossmember? I know where the panhard bar will mount, and how and where the arms mount, just not sure how to locate the shock crossmember?

Can anyone help? Thanks...