Convert Bobcat SGX60 to a SG60 ... Swap motor head ?

[Trailman24]

Over the phone and internet, I agreed to buy what was supposed to be a Bobcat SG60 stump grinder to use on my Bobcat 853 Std Flow Skid Steer and My ASV 4810. Drove 550 miles and found out it was a SGX60 for a high-flow machine. Drug it home and turns REAL SLOW on the 853. Could I get a hyd motor head for a SG60 and use it on both, or swap when I switch to the ASV 4810 ? Wonder what kind of $$$ I would be looking at. HELPPPPPPPPPPP !!!!!!!!!!!!!!!!!