Those look pretty nice. After you have installed the engine, taken the dash out and ran the 7mgte wireharness through the firewall your gonna need some specific information for two subharnesses. One of those specifics is some info on how to make them and what too connect them too (how many wires and pins). The smaller harness is connected under the engine bay fusebox and the other larger one under the dash. I can't give you any specific advise because I did almost no work on the wiring. Don did most and my dad the rest, *shrug*. The problem with the diagram is that every figgin' year they (Toyota) changed the wiring colors and cfg's. Forexample: a '82 Supra with a '89 engine is gonna need a different different harness than a '85 with a '88 engine. If you get a TSRM wiring manual for the 7mgte you have say '89 and one for your Supra '83 (If that's what year it is) then you might be able to figure out what is needed as far as the subharness. I really wish I knew more about these wiring conversions. You might call Don and ask him about Larry's harnesses. Larry is the guy who makes the connector harnesses for Don's conversion kit. Perhaps would sell one with instructions for the right price.