coolant leak on 1990 Mazda B2600

my truck is leaking coolant from under the intake manifold in not shure if it is a head gasket or oil coolant line or heater core return line what is the easyiest way to determine where the leak is coming from
this is a 1990 b2600I 2 wd dr

Asked by for the 1990 Mazda B2600
You have to get in therte and look with a flashlight and mirror and see for yourself. I think there are some small coolant lines under there but it's been a long time. It could be a head gasket, and you should be able to see if that's so. Either way, you'll see deposits and a trail of the leak.