http://chevy.oldcarmanualproject.com/chevyresto/4990.htm

The Optima 6v battery fits in the original 47-55st battery tray and can be installed diagonally with the original battery retainer/hold-down.

Use felt anti-corrosion rings (and conductive anti-oxidant grease for both connection ends of both cables).

Both the positive cable and all ground straps/cables should be no smaller than 2 gauge and could be as large as 00 gauge.