Assuming you have factory Timken bearings, gear lube leaks are the inner seal,not the outer.
I used a slide hammer to hook behind the seal and pop it out.
I think the 1 1/4 socket for the balancer bolt is the correct diameter to install the new seal..
Pack some wheel grese on the inside of the seal to hold the tension spring in place while installing, they tend to come off while you are installing the seal.
Also pack the rear bearings like a front wheel bearing, gear lube does not lube them..
Yes you must use the good gear lube additive, Previous posters on this subject recommend the Ford stuff..