Right side? Passenger or Drivers side?
If drivers side, then it is likely either a cracked coolant crossover where they all crack or cracked around the thermostat due to over tightening. If passenger side, look at where the heater hose goes into the intake, if brass it can leak/come apart, if plastic it can crack.
Most likely source of the coolant leak is the lower intake/plenum.
The state of Arizona is sorta a big one, I live in Tucson and I got a new windshield installed at my house for 145 bucks. I don't remember who installed it, I then found out I had 0 glass (full coverage on an 89 Cougar, hahahaha) and had them reimburse me.
97 Mark VIII LSC/Silver/Gray leather
97 Cougar 4.6 Sport/White Opalescent Tricoat Metallic /Gray leather down but not out?
89 Cougar LS 3.8/Oxford White/Gray velour/HG need replaced AGAIN
00 Grand Marquis LS/Vibrant White/Gray velour
63 Falcon 302/black and rust/shed isn't moving
82 F-150/Oxford White/dumb VV carb doesn't pass emissions