Preparing for frame/chassis build

[Macnasty]

I recently obtained a complete K-member from a 74 chevy for my 5 lug conversion, got it for the fair price of free.99. This is just what I needed to get the ball rolling, and I'm pretty pumped about it. I'm taking my vacation next week and plan on getting the chassis ready for the body. I really only have one question as I have spent many hours in the FAQ preparing for my frame-off build (first one). I will be using the NV3500 but have yet to aquire it, however, I would like to know where the transmission crossmember needs to be so I can put it in its respective position and have a rolling chassis ready for drivetrain and body. I hope I am headed in the right direction. Any advice is greatly appreciated.