Heater Core from www.autohausaz.com ??

[Frederick Smith]

The following web page shows exactly what I meant about the different 
cores. The core
pictured in the top photo is the one that produces the least heat. 
Generally Nissens and
Behr are good ones. (It's a long link, hope it works!!)

<http://catalog.eautopartscatalog.com/drivewire/baseline/wizard.jsp?partner=drivewire&year=1988&make=AU&model=5000-QT-001
&category=R&part=Heater+Core>