Replacement for BB-CT92E 68/116

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I have a 1999 Trek 820 AL whose bottom bracket is dying.  According to the spec sheet, it's a Shimano BB-CT92E, 68mm shell, 116mm spindle, English threading.  What is the easiest way to identify a suitable replacement?  I found a NOS BB-CT91 with the same measurements on eBay for $20, any reason not to pull the trigger on that?  Thanks!