I don't have access to an air impact wrench so I will have to try it from the top.
I think these are the models with the belt retainers that are part of the frame, so the recommended procedure it to removed the PTO clutch to repalce the drive belt. That's a lot of work if you ask me, plus the pulley probably isn't going to just slides off the shaft without some encouragement.
Since the drive belt is under tension full time I don't know why they thought they need those silly tabs to hold it on, because the belts not going to come off the pulley.... so, here are your options...
1) Cut off the tabs... I actually did this on a neighbor's mower, they are just 12ga sheet metal that's bent downward from under the motor and at first I tried to bend them out of the way, but that proved less than useful so out came the angle grinder and off them come in about 60 seconds... slipped the new drive belt on and was back in operation in less than a minute... didn't replace the tabs with anything... I told him if the belt comes off we can take some 1" angle iron and sheet metal screw to recreate the tabs and make them removable! But so far that hasn't been needed and that was over 3 mowing seasons ago.
2) Loosen the motor mounting bolts and tip the motor forward... I heard that this will give you barely enough room to slip a new belt on. Still seems like a lot of rigmarole just to replace a belt!
3) Take the PTO off... my neighbor actually was going this route -- after all this is what's listed in the service manual -- but, after soaking the shaft in penetrating oil for days/weeks and putting enough pressure on it with a puller to start distorting it... mind you this was on a tractor that was roughly a year old... so, he thought better of himself and that's when he called me over to take a look at it.
I firmly believe that taking an angle grinder and removing those silly tabs is a perfectly good long-term solution... it certainly makes future drive belt replacements less painful!
BTW his tractor had a standard belt, but the replacement was a kevlar reinforced kind.... which is probably why the first one wore out so quickly... you might check to see if the kevlar variety is available for yours too.
.
