Radiator Flushing

[rkn2903]

How many gallons of antifreeze will i need to do a 50/50 or 60/40 mixafter flushing my radiator I have a 99 5.3l GMC seirra SLT 1500?

[MS3DALE]

Two gallons should be enough! Might not be a bad idea to change your thermostat and hoses while your at it,but remember the thermostat is part of the whole housing asm. but its not that bad to change.