Just replaced a starter on my skid steer with this method since it also was a one-handed job. Got a couple of manifold studs the right size as guides. Finger tighten a nut on one before removing the other one to hold the starter in place to replace the stud with bolt. Yes it was a gear reduction starter which made everything a little lighter but since I am 85 everything seems a little heavier.Do it the super safe and easy way.
Remove both battery cables . Make sure they can not touch battery posts.
Remove the TOP starter motor nut or bolt. If a bolt ? take it to a hardware store and buy 1 bolt that is same diameter and thread size. Make sure it is about 1 inch longer. Cut the head of the bolt off. Put it FINGER tight into the motor hole. Now do the same thing with the bottom bolt. Remove electrical parts from the motor.
BEFORE sliding the motor off those guide bolts. If you drop the motor ? No good parts are damaged. Those 2 headless bolts are the only way to do starters.
BTW, what the heck does "PMGR" stand for?
I did the heavy Delco style starter one handed on my 4.3 2x over the years, you could lay a 2x4 across the gunnels and tie a line to the wood and then use that to tie up the starter to hold it while you get the bolts started. The PMGR are like half the weight. Make sure you use the correct length bolts; if they are too long they can allow the starter to shift under torque & break the bolts off in the block. That will put you in a world of hurt!
I would definitely replace that direct drive starter with a PMGR
not only is it half the weight, it will spin your motor over faster when starting