when i turn on my left blinker, my fuel gauge bounces with the blink. (this is on my 1955 belair)

If it's mostly the original wiring ? "check you have a good ground to the back of your dash", (all steel) dosen't always mean a good ground, could also be poor positive supply to the gage, old wiring = more resistance= less voltage, check charging system ? check voltage at fusebox with engine running, 13.5v aprox ? voltage stabalizer (if it's got one) shot ? but don't all 55-56-57 etc. do that to some extent ?
dave