Tony Moore wonders about his 83.5 running too cool.  I recall going 
through something similar on my 84 a few years ago.  It turned out to be 
a thermostat stuck OPEN.  The gods must have been smiling on me for it to 
have failed that way!  I could get the temp almost all the way down to 
the cool range on long coasts down hills!  I replaced it and things 
returned to normal.  Give some consideration to replacing the water pump 
while you're in there, unless it was recently replaced.  You'll need 
pretty much the same gaskets to do both as to just do the 'stat, and 
you're going to have to drain the coolant anyway...job should take about 
3-4 hours, depending on what else you do too.

Rich Schmittdiel
84 GL