Injection nozzle retaining nut socket

Anyone out there have a Cat part number for the internal splined socket that is used to remove the nut that holds the injection nozzle in the pre-cup on a D315 engine from a 955 Traxcavator, s/n 12A4296 motor? The splined nut is about 1" in Diameter. I don't have any info on this unit. Most of the other retaining nuts are hex shaped. This must have been a year all it's own. Thanks in advance, Larry.
PS. Have a bad injector nozzle, that's why a socket is needed.

Hi Larry,
the splined wrench/socket is P/No 2H7479.
Scaned below is a pic of the tooling for the Glow Plug precombustion chamber Direct Electric Start engines.
Hope this helps.
Cheers,
Eddie B.

Also goes by the earlier number 8S2243

Many thanks edb and Old Magnet. Have one ordered. Larry.