To install a locker that requires replacement of your differential carrier, like an Ox locker would, will require them to install the ring gear from your carrier onto the Ox carrier and adjust the shims between the bearings on each side of the new carrier and possibly the shims on the pinion in order to get the correct contact pattern between the ring and pinion gears. This will provide the opportunity to correct if it is not currently correct. However 99 out of 100 shops will not take the time and the trial and error it takes using Prussian Blue to get the correct pattern. They mostly just transfer the shims you have installed and call it good, as what the customer does not know is all good. If you want it done right, you will need to do it yourself, and you will need a press, a bearing splitter, and it will be helpful to create a set of oversized ID setup bearings to get your shims in the ball park to avoid having to press on and press off your good bearings too many times trying to get the shim stack just right to get the contact patch just right. That is one of the advantages of a lunchbox locker which just replaces your spider and side gears and you do not have to reset up the ring and pinion fit because you are not replacing your carrier or ring and pinion gears.
