Hi John,
the data I posted is the latest I have here at home. Undercarriage was not my field of expertise so I'm not able to answer your questions exactly.
The two columns of 951 specs covers the two pitches then (1991) in use on the 951 up to that date. Line 2 of the chart gives the pitch relevant to the undercarriage fitted to a machine. If your pitch is not one of these 2 then my data is too early and sorry I cannot help further. Also I do not have Parts Books for any Traxcavators.
Cheers,
Eddie B.

I don't have much info on 951's but I have some literature that indicates the 951C uses the 7K3995 sprocket rim as opposed to the 951A & B which uses a 8A1378. Also appears as AJ stated, that the segmented sprocket option never did make it to the 951 series.