Here you go masters of the 20r. The patients (1979 toyota pickup) symptoms are...

1) overheating
2) coolant in oil but not any apparent oil in coolant
3) coolant disappears from radiator over time with no apparent leak
4) radiator flows and but may be bubbling up a bit
5) no visible smoke out of the exhaust
6) engine runs fairly well

What do you think?

Thanks for your help / Caroline

 

Sounds like a head gasket, or cracked head to me.

 

also chain may have worn through the timing cover and into the coolant jacket

 

Pull that head and have a machine shop check it for cracks.