There is no set science,these cars were built with the plus/minus factor and tweaked to try to make things fit and work.Sometimes they did and sometime they didn't and some took a lot of refining to get them to go down the track.Find (if you can)two original (Amblewagon) units and you will see a lot of varaiations between them,similar to the Hurst Darts and Cudas.We are talking Chrysler and their contractors,these we hand assembled not done on a exacting scienced production line.Some of the originals were bodys proped on concrete blocks while the metamorphasising was being done.Some were half finished and fine tuned by Alexander Bros/Branister as well as the racers who recieved them.