My 56 has a cable from the neg side of the battery to a captured nut on the lower right side of the firewall. From that connection it has another cable to a bell housing mount bolt. I believe that to be similar to the factory connections. Use star washers at the connection points. Grounds do not work well with new paint.
Fred


1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine