If I was changing out mine, I would remove the upper coolant hose from the thermostat housing. First drain some cooling off into a clean container using the petcock. Then remove hose from thermostat hosing only, I would a wrench instead of a socket to loosen/remove the ect. Use either a thread sealant or teflon tape on the ect threads and install. Reconnect upper hose to thermostat neck. Top up coolant level in radiator and overflow if needed.