1. TCI sells a 4 bar for 1954 3/4 T. I will assume they tried to give him that kit. It is not the same kit as 1/2 T. 1/2T frame is 46" wide and 3/4 is 36" wide.
2. I don't know if that S10 graff is complete. Don't see a fish plate or anything but a partial box plate????
3. The TCI kits don't require boxing. Other types of modification kits do. Many times it's just for a plate to attach something to and give local "strength". It depends on the goal. In general, when "hot rodding" a truck if you want to increase load capacity, you box. If you want to strengthen twist, you add crossmembers. you can do both. Most of the Companies use "theoretical" Engineering. Many web articles are DIY engineers. (AKA Hot Rod Shops).
None of these kits have been tested in a lab, FEA, structural analysis, load calculations for every scenario and etc. The only builds that are structurally engineered are 8000 HP Top Fuel Dragsters, Funny Cars and Formula 1. Much of the design is driver safety related. Hot rodding a truck sometimes takes strengthening depending on Big HP, torque, weight transfer, etc. Dropping a 350 into a truck takes nothing.
4. For reference. Some old trucks have ladder frames, some X. Look at an aluminum ladder, it's frame is a C channel, the crossmembers are the rungs. You can use it as a foot bridge across a ditch. Take out several rungs and it will twist...... (I know, some are I beam frame, some are rectangular tube).
