? part in Lower ball joint parts bad

Is this blue plug for my vehicle? I called Raybestos and the tech dept said "it goes in the axle and you need a special tool for it." I said maybe it's for another vehicle that takes the same part # and when I told him I had a 1996 Jeep Cherokee, he said I need it?

When I took my stuff apart, I had no such part

FWIW, this parts bad had 2 blue plugs (while the other had 1) and no lube plug fitting, just a lube fitting.

Older D30 used those blue threaded inserts, newer ones do not. 1996 does not.

Thanks Tim - mystery then solved. I pressed the left side joints in last night and will do assembly this am. Then I can take it in for annual state inspection. Thanks again for the reply, Fred