I am finishing up some maintenance on my Perkins (4.108) powered generator. It started with a concern with the age of the raw water pump impeller which required the pump's removal. Then, why not all of the hoses, relatively easy cuz it's just hose. But, the heat exchanger step-down end caps are a different story. Mine looked to be original, maybe 30yo. They were squashed, painted over and scary looking. On this and on other forums I have read that Perkins parts are expensive. Well we all know the word "expensive" ought not be in a boater's vocabulary.
Anyway, I googled the Bowman part number that is embossed imto one of the two end caps. The cheapest US source I found cost $68. In addition, it requires three differently-sized hose clamps to complete the installation.
I found a supplier in England instead. I paid $46 for BOTH end caps, INCLUDING six clamps. Shipping was $23 via Royalmail air mail. Perhaps there is a US supplier that can match these prices but I rather doubt it. Oh, the vendor was parts4engines.com.