First things first.
The '65-'66 Mustangs had the Eaton Pumps, which had separate reservoirs. A leak between the pump and reservoir should be a piece of cake. A leak at the shaft seal, I'd suggest getting a remanufactured pump from your local reliable parts store. You will need to have use of a pulley removal tool. If yu buy a replacement locally, the store will switch it out for you. The problem with sending yours out, is it will take some time to find out if yours is repairable, and then you need to wait for it to be returned. Then, if there's something wrong still, you go through the same time-consuming routine. If it's not repairable, you need to wait for return so you can use it as a core to purchase a replacement. I have an O'Reilley's within a block, and can just walk back down there if something is wrong with the remanufactured unit.
There are three places for a Thompson pump ('67 to ?) to leak. The front seal, the canister or reservoir seal, and the rear/output gasket/seal. To do any work on theses, you will need to remove the pulley, before removing the pump from the mount. The reservoir and rear/outlet seals are easily replaced after popping off the canister/reservoir. Reassemble after cleaning and lightly lubing.
The front or shaft seal will require disassembly of the pump itself. Unless you're pretty confident of your abilities with pumps, I wouldn't tackle it. I'm a former AF Hydraulic tech, I didn't disassemble mine; because the instructions weren't complete enough. If it's leaking out the fron, get a reman pump.
The '65-'66 Mustangs had the Eaton Pumps, which had separate reservoirs. A leak between the pump and reservoir should be a piece of cake. A leak at the shaft seal, I'd suggest getting a remanufactured pump from your local reliable parts store. You will need to have use of a pulley removal tool. If yu buy a replacement locally, the store will switch it out for you. The problem with sending yours out, is it will take some time to find out if yours is repairable, and then you need to wait for it to be returned. Then, if there's something wrong still, you go through the same time-consuming routine. If it's not repairable, you need to wait for return so you can use it as a core to purchase a replacement. I have an O'Reilley's within a block, and can just walk back down there if something is wrong with the remanufactured unit.
There are three places for a Thompson pump ('67 to ?) to leak. The front seal, the canister or reservoir seal, and the rear/output gasket/seal. To do any work on theses, you will need to remove the pulley, before removing the pump from the mount. The reservoir and rear/outlet seals are easily replaced after popping off the canister/reservoir. Reassemble after cleaning and lightly lubing.
The front or shaft seal will require disassembly of the pump itself. Unless you're pretty confident of your abilities with pumps, I wouldn't tackle it. I'm a former AF Hydraulic tech, I didn't disassemble mine; because the instructions weren't complete enough. If it's leaking out the fron, get a reman pump.