[AussieinNC]

The difference in the thread size (and there are only two that I know of) is early and later series.....

On the solenoid dismantling, there are two nuts on the end of the body, undo those and the end will come off the solenoid.

The shaft seal is available by dimensions from a large bearing supply shop...it is contained in the overdrive case itself, not on the solenoid itself.

When you get ready to install the solenoid the first thing you want to do is line up the solenoid shaft so the flat spot is at the 12 o'clock position. Next apply battery power to the number (4) terminal on the solenoid. Then ground the case of the solenoid which will make the solenoid shaft extend out. Now carefully slide the solenoid shaft past the seal (a little white grease or Vaseline in the center of the seal and on the end of the solenoid shaft works wonders) until the shaft engages into the pawl in the transmission. Once it is engaged turn the solenoid to secure the pawl into the grove of the solenoid. Release the ground and the solenoid shaft should retract... and if you got the pawl into the groove at the end of the solenoid shaft correctly the solenoid itself will be pulled towards the transmission. If you always install your solenoid this way you can be 100 percent sure the solenoid is installed correctly. Line up your bolt holes and you are done.

Note....if you find you need a new solenoid, the shaft length that sticks out of the body comes in two or three different lengths...make sure the old shaft length matches the new unit.

The solenoid uses two coil systems, one to engage and one to hold in position...so make sure the solenoid is the correct voltage...you cant use a 12Volt solenoid on a 6 volt vehicle...by using a voltage divider.

If the solenoid tests ok as far as moving the shaft in and out...I would leave it alone....there are really no servicable parts inside the case.