Sorry , but I am not that knowledgeable about this stuff.I don't know what a fish plate is. This is a pic of the car when I got it. The subframe connectors were already installed and are quite solid and heavy duty. See pic. All he is doing is boxing them in so they look like a frame rail that belongs there. I hadn't planned on adding any more braces or tailshaft loop. Not going to be used for any drag racing or road course stuff. Just a nice cruiser with plenty of power and modern suspension, brakes and engine management. Being a convertible, the connectors are almost a necessity. Body flexes and things get out of align.