So I am trying to get a replacement chain for my Surly LHT.

Surly list the chain as a SRAM PC-971, but the one I bought is about 2 links shorter than the one it came with.

SRAM list three chains - PC-991, PC-971 and PC-951 but their site gives no information about them.

Does anybody know the difference between them?

I would prefer to buy one too long and take a couple of links out, giving me some spare links, than add links...

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