I'm not an engineer, but I have built many structures and made my own trusses for several of them. In order to gain height for two of the observatories I built I made scissor trusses. Easy to make, and should be able to modify an existing truss. Essentially rather than having a 2 x 4 running from wall to wall (to prevent walls from spreading under load and letting the rafters fall) a 2 x 4 is run from the top of each wall (attached to the bottom of the rafter) to about 2/3 of the way up the other rafter. Where the two cross they are bolted together (with a spacer the thickness of the rafter). This makes a nice solid set of triangles, which gives the set up structural rigidity. If you look up scissors truss on google you can see what I mean. It wouldn't involve removing the existing truss, just removing part of the center of the existing truss AFTER the scissors are in.
I'll see if I can upload a drawing.
Tim
I am currently digging back in to a 1953 3800 (one ton) with a nine foot bed. I've owned it since 1979, and drove it until 1982 (or so). My wife got me involved in restoring it back in 2002, got the body removed and the frame redone, then things came up. Now I am retired and starting again. If anyone is interested I have photos on Imagur ( https://timwhiteblues.imgur.com/ ). I live way back in the woods in the Ozarks on 40 acres at the end of a 2 1/2 mile private road.
