80W90 unless your nursing failed seals. Cornhead grease is for a 49 rear gearbox. Cornhead would probably work fine in this application but if it was mine I'd use the factory fluid. A friend with a bolens 2 stage had his gearbox go out and couldn't find the shaft and told me how he'd fill it every use and it was still steaming hot when done. Cornhead grease fixed him up. You should have seen the smile when he said the gearbox stayed cold.