I'm trying to figure out if an inline coolant heater would circulate properly when installed on the lower radiator hose, and if anyone knows what the inner and outer diameter of that hose are

Thanks for your time.

 

Not sure on the dimensions but you could do it off of a heater hose pretty easily or the 1/4"-3/4"coolant hoses on the throttle body. Just make sure whatever you use has a thermostat.