T & PYou should be able to pick one up at any hardware store just make sure its a short one. They are not to hard to put in. Like the others said work the valve a bit if it still leaks might have to replace it.
Could be 1/2" or 3/4" thread Any hardware or rv store They open at 150 psi/210*F (reset at 125 psi)
2006 it may need replacing.........may Have you exercised the valve......stand back and open valve via lever with water turned on (water heater off and cold). Let it blow and then let lever 'snap' closed. Do a couple of times to clear valve/valve seat of any build up/debris
Also it is NOT uncommon for them to weep when heating the water if the air pocket in top portion of tank has been lost (water doesn't compress---air does---water expands/swells when heated---no air to compress then pressure increases) Air pocket is normally established when filling water heater. Over time the air can get absorbed into the water
To re-establish air pocket Turn water OFF Open closest faucet to relieve pressure on hot water Open the PRV until water stops draining out.....then let it snap close Turn on water Close faucet