You will need the serial number of teh unit to assure you get teh right parts. It is stamped on the unit - keep looking often the s/n have been painted over & it will take some effort. A common place to find the s/n is on the front frame member between the mast tilt cylinders. If the data plate is metal (aluminum) simply remove the paint and the model numbers & s/n will appear - the model number will start with GLP or GLC followed by 3 numberc like 050 followed by a letter A or R etc and more letters & numbers. The s/n will be all number except for one letter that will give the year of manufacture (you have to have a Captain Midnight decorder ring to translate that letter to a year or your nearest Yale dealer can help you)