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If you are asking because you want to upgrade to the 2 piece thermostat/housing, if you use the 2004 PN and the 2004 thermostat housing and thermostat you will be golden.
The PN is AC Delco 251744 and that is the OE. Do not use the Professional series for half the price. I just went through all of this and trust me, you want the OE one. The others have a different size thermostat hole and it's just a pain in the ***. This will list as a one year pump for 2004. The others will say fits 97-04.
When you upgrade to this, your thermostat will have the gasket ring attached to it and the outlet will just be an outlet - no more one piece housing/thermostat.
But I believe the LS2 pulley is less in depth and the pump above will have the larger dome. Diameter is the same I believe, just depth.
Also, I used the Fel-Pro steel water pump gaskets with integral rubber seals. And order a set of water pump bolts for like 12$. Amazon has them avail. The gaskets are probably weeping and better to spend 12$ and not need them than be sitting with rusted out bolts.
Below are screen shots from Delco and Rock Auto.
Last edited by Ed Ramberger; Jan 25, 2020 at 12:12 AM.
If you are asking because you want to upgrade to the 2 piece thermostat/housing, if you use the 2004 PN and the 2004 thermostat housing and thermostat you will be golden.
The PN is AC Delco 251744 and that is the OE. Do not use the Professional series for half the price. I just went through all of this and trust me, you want the OE one. The others have a different size thermostat hole and it's just a pain in the ***. This will list as a one year pump for 2004. The others will say fits 97-04.
When you upgrade to this, your thermostat will have the gasket ring attached to it and the outlet will just be an outlet - no more one piece housing/thermostat.
But I believe the LS2 pulley is less in depth and the pump above will have the larger dome. Diameter is the same I believe, just depth.
Also, I used the Fel-Pro steel water pump gaskets with integral rubber seals. And order a set of water pump bolts for like 12$. Amazon has them avail. The gaskets are probably weeping and better to spend 12$ and not need them than be sitting with rusted out bolts.
Below are screen shots from Delco and Rock Auto.
Thanks order through amazon since they are easier to deal with if there is a part issue. Got the pump new, housing, and 8 bolts. I guess the thermo housing does not have a gasket? It only uses the thermostat oring??
Thanks order through amazon since they are easier to deal with if there is a part issue. Got the pump new, housing, and 8 bolts. I guess the thermo housing does not have a gasket? It only uses the thermostat oring??
My original pump was in leaking to the weep hole
If you ordered the OE pump I gave the number on, the hole where the thermostat goes will have plenty of meat for the rubber ring to sit on - and it fits snugly into the housing into a relief. There will not be a paper gasket. The one that fits all years has a hole that is about 1/4" bigger in diameter and the rubber ring will not seat. It would then require a o-ring and a gasket. Your one piece thermostat & housing will not fit into the hole. CHECK THIS FIRST to be sure you got the correct pump.
When you seat the new thermostat you will put it into the housing (the notches will line up with the jiggle valve/gasket and housing.) There will be a little spring tension as the spring loaded plate sits against a ledge inside the pump. Snug down the bolts. I believe the spec is something like 100 lb/in.
Last edited by Ed Ramberger; Jan 26, 2020 at 07:29 PM.
