Battery in trunk wire routing.
In the 69 Cuda I ran mine inside the car all the way (both + -). Run the cables under the scuff plates so all wires are hidden and safe. At the Fire Wall I used an unused oval gromet near the brake pedal and drilled 2 holes just a bit smaller than the actual cable (one for + and other for -) so it is a firm fit and is still water tight. Positive cable to Starter - of course and negative to the transmission. After that make sure you put some earth straps from the body to the block and I also ran an extra one from the battery to the body.
In the 69 Cuda I ran mine inside the car all the way (both + -). Run the cables under the scuff plates so all wires are hidden and safe. At the Fire Wall I used an unused oval gromet near the brake pedal and drilled 2 holes just a bit smaller than the actual cable (one for + and other for -) so it is a firm fit and is still water tight. Positive cable to Starter - of course and negative to the transmission. After that make sure you put some earth straps from the body to the block and I also ran an extra one from the battery to the body.