Classic/Antique Car Repair: 1946 buick, gm cars, brands of cars

Question
is electrical system pos/ neg

Answer
I'm guessing you want to know which terminal of the battery is grounded - right?  All GM cars are negative ground (the negative terminal of the battery is grounded to the chassis and engine).

Many if not most of the other brands of cars were positive ground until the mid 50s.

Dick