Coolant confusion

I need to change the thermostat in my 70's 6000lb Yale forklift so will change coolant at the same time. It's an aluminum head Mazda engine with conventional copper and brass soldered radiator. The guy at Yale says use borate and silicate free, the new antifreezes are designed for aluminum crimped radiators and some will attack the solder used in older conventional radiators. It has green in it but I'm not sure what kind. Anybody know what coolant should be used? Tempted to put Cat ELC in...

Coolant confusion

Coolant confusion