Looking for a reputable source for aluminum coolant pipes, water pump, crossover pipe etc I do not want to buy from just anyone and have the pipes not be proper fit

Euro AMP on Ebay ?

 

"Aumzong" rear coolant crossover w/sensor on amazon was $109.99, fit perfect.

forum favorite or at least quite popular "RKX" kit with both front pipes and water pump pipe in alum. with extra seals included on Amazon, $139 ( comes with spare optional smaller O rings I had to use, water pump fitting/o ring / brass elbow)

water pump locally was over $140-180 my cost being at a dealer - exact same thing on Rock Auto (GMB) for $80 shipped. even came with new screws. single gasket casing.

i had to rtv lightly around the reservoir outlet on the new metal piece, and zip tie the fitting for good measure, but I think this is more common than not.