flush tee location

dieselsite coolant filter installed and want to flush for red coolant install. which heater hose to install TEE in? upper? lower? thanks

come on guys, help the less fortunate out if ya noz sumpin! say on onlet side but...cant see 'nuf to figure which is comin, which is goin.
top? bottom? thanks, richard

I'd say upper hose.

thats where l was heading, thanks mike. richard