Ford 9N Hydrolic pump question

We need to replace the fan belt, upon trying to disconnect the front mounted hydrolic pump for a dearborn loader, we found out the pump was frozen, the the front collar that mounts into the engine assembly is a 4 pronged assembly that fits in the engine.....here is the question.....how does this 4 prong assembly fit on the shaft that mounts with the hydrolic pump....does it have a key fitting or is it another way.....we couldn't get it off, so we soaked it with WD-40....my Dad seems to think that it has a key fitting, but was not able to obtain any information on this.....any information would be great....Thank you very much

I don't think though that the shaft would have to come out to remove the pump. The other end of the shaft should be splined so it will pull out of the pump. Might try the penetrant at the front of the pump and them use two prybars to try to get the pump to release the shaft.