How did you install your flatbed?

I am formulating my plan for a flatbed project.
my truck is my dd so I am going to build the bed on a table then transfer it to the truck when it's complete.
I have no idea how heavy the new bed will be. It will be all steel.
maybe just build the frame first then put the deck on once it's on the truck?
I only have a 2 car garage and its by no means empty.
maybe either an engine hoist or chain stay from the rafter?
have some friends that I can persuade with beer to help muscle it but not sure it would be enough manpower since I don't know how much weight I'm looking at.

The attached picture is roughly the look I'm going with.

 

What is the purpose of the flatbed? All flatbeds for full size trucks are much heavier than the factory bed. You can make yours however heavy/light you want. You mentioned using the rafters of your garage- be careful. Most rafters for residential garages I wouldn't trust supporting the weight of a flatbed. Plus you should get a pulley system rated for overhead lifting applications.

I've considered building a flatbed except for me needing the bed to haul soil, stone, etc. If/when I build one I will build it on the ground and then lift it onto the truck with a few friends' help.

 

Mine will mainly looks. maybe mulch once a year?
my garage has a 18" high x4" wide beam running thru the center from left to right. It ties the house together. Garage is about 50% into the house structure.
I will most likely use an engine hoist with a couple friends for help though.

 

Heck, if it's mostly for looks then you could build it out of 1 inch square tubing and cover it with diamond grate (yes, I said grate, not plate). This way it would be strong enough to strap a few things down and it would be light.

 

I think I am going to use 1 inch square stock but am going with diamond plate for thw floor. Would rather have a solid floor.