If your mower is an Evo 3 Mk 2A, not an Evo 3 Mk 2, we have been discussing the wrong mower. Here is the Mk 2A steering parts diagram:
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Here is the corresponding parts list:
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What I would describe as the king pin bush is Item 8, Part Number GT12394. Note that 4 of them are required: right and left, upper and lower. Do not omit the thrust washer, GT2018, which must be placed between the underside of the front axle, and the stub axle, on each side. Note that these parts are identical to the Evo 3 Mk 2 parts.