D315 pre-combustion chamber

I'm new to ACMOC and diesel mechanics. I bought 7U10608 last November. Pre-combustion chambers were old (possibly original) and badly pitted. I'll pass along here what I discovered in my search for replacement pre-combustion chambers for the CAT D315 engine. Old hands won't want or need the following information but newbies like me might appreciate the shortcut to "pre-cup heaven". First, the original chamber assembly, 4F8517, is no longer available except possibly as a used part (I never found one). Second, the CAT replacement for 4F8517 is 2S1273. Don't be fooled that 2S1273 is of a different design than 4F8517. 2S1273 looks different but it is the proper replacement. CTP sells 2S1273 under their part number 1S1970 (Does CTP manufacture 2S1273/1S1970? I don't know but what they sell is brand, spanking new, not new/old stock. Can someone clarify---Who makes the new 2S1273/1S1970?). Heavydutypros.com offers CTP 1S1970/2S1273 for sale, as do other aftermarket vendors. Agkits.com has it in stock for a most reasonable price. The required copper seal and o-ring are still available under the original CAT part numbers.

I have some D315 pre-combustion chambers nice condition