There are two different types of rear axle models for your vehicle that are also used in different Toyota truck applications. There is the model commonly referred to in the aftermarket as the Tacoma 8" and another model referred to as the TRD Locker 8". The part number of the gear that you provided is the one used in the TRD Locker model.
Some later applications (TRD Locker style models) require a new yoke to adapt to aftermarket gears. If the inner and outer pinion bearings are compatible with the gear you received, this may be the case. (If this is the case, we may be able to provide the adapter yoke to you at no charge. You can reply to this thread if you can verify that this will resolve your issue.)
If the actual pinion stem diameter is larger on your original pinion then you would have the Non-TRD standard axle requiring the Tacoma style 8" standard gears.
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