Yet another GMC build

[dsraven]

start with a good power wash.
also, before installation, flush out the cooler lines and replace the cooler.all that stuff is stuck in that old cooler. some will put a filter inline but I am not on that side of the fence, personally. I have seen a hydraulic shop flush new lines and then blow a plug down the line with compressed air to clear any solvent from the line and see if the plug comes out clean or if the line needs more flushing. they use what looks like a roll up ear plug.