thermostat outlet diameter

[Prince13]

whats up guys, need help on this here. im due for a water pump since mines is leaking indicating its on its way out if it isnt out already. my question what pump do i need to use since i see theres pumps that have different thermostat outlet diameters. any help is appreciated. thanks in advance guys. my truck is a 2001 5.3 liter

 

[SnowDrifter]

Just buy both the pump and the tstat, shouldn't have any issues there. Good practice to replace the thermostat anyway when doing a radiator or water pump