98-12v has white smoke

[jwracing]

I am Looking at buying this truck. Its a 98 12v 5 speed. Truck runs good and has decent power for being all stock including exhaust. Motor has 281k on it. Just an old work truck. The motor has white smoke at all times Temp at 185. idle, driving, running 70 down the highway. Motor doesn't get hot but could smell antifreeze. I assume it's a blown head gasket. Just looking for answers and other causes it could have. Thank you very much