I used welding cable and got high quality terminals from a United Delco dealer. I soldered all cable terminals and used different color of heat shrink to identify 12, 24 and ground, Notr that some terminals can only be soldered and some can only be crimped. Some can be either or both. I also relocated the engine batteries to the engine compartment. The only high current draw on the engine batteries is the starter so I put the cables (both positive and negative) direct to the starter. From the starter ground go to the engine cradle and then to bus chassis. From starter positive go to the original cable terminal on the rear bulkhead. If you are replacing the front to rear cable it is 0000. If you are not using original bus heat and have the batteries in the rear then #2 is adequate.
David,As already posted. those starting batteries need to be as close to the starter as possible since that is the primary use for them.You probably have a good reason to move them to the front but electrically it makes no sense.