Presumably, the model number of the actuator will be stamped into the metal of the casing. This can wear down and/or get painted over after many years of service. If you cannot locate the make and model on your actuator, you may be able to go by the measurements.
I went out to the warehouse and measured replacement shock # DS12426. The overall diameter is 1.662 inches (about 1-11/16 inches). The larger eye has an inner diameter of 0.89 inches (about 7/8 inches). The smaller eye has an... view full answer...