Worked out well that the next cross member also supports the upper control arm bracket and will stop any twisting of the rail from the lower arms as well.
The brackets to support the rear and centre tank straps have been added. The front tank strap will bolt up under the floor into the original mount as I will be using that and the firewall from the donor.
Doesn't look like it, but made the closest new cross member sit level with the rear part of the frame so it will support the bed floor as well. Next photo shows it better.
Extended the cross member all the way down to the bottom of the frame rail. Improves its appearance and and adds further strength and weld area. I checked before welding across the top of the frame and found several frames like the Holden Rodeo, Dodge 1500 etc, which have the same cross member arrangement sitting on top of the chassis, where they had fully welded it the same as shown. Not always recommended to do this, especially if you have a frame with flex in it, so do your own research first.
Can see how the original cross members look very similar. They are the same dimensionally and have the same bend angle and radius. The bends are just closer together on the originals which meant they wouldn't clear the tank.
The new ones are stronger being fully boxed rather than channel and are rust free.
Poured some lanolin oil down inside and rotated them to coat all the sides before welding them in to prevent rusting.
Only one more cross member to add now which is the very front one. It goes under the grille and radiator area so can't add that until I know the exact placement of those.
The frame has ended up remarkably similar to the new 2013 Dodge Ram 1500 frame which even has an option of the same 5.7 HEMI.