Yamaha 30hp 3 cylinder water pump

[southARbuck]

Looking at the schematics from boats.net, there are 2 water pump kits for the MSHX and I was wondering what the difference is. 6J8-W0078-A2-00 vs 6H4-W0078-0A-00 are the 2 part numbers in question and I just need to know why there are 2 that fit this motor?

[99yam40]

maybe one is a rough service one

[boscoe99]

The chrome kits are more durable. Especially for those that operate in sandy or silty water.

[southARbuck]

Thanks for the responses.