Need tips for changing PTO lever seal

I have to change a leaking o-ring at the PTO shift lever on a 73 Ford 3000. Any special things to watch for, other than drain oil some, make sure to line up the shift fork with PTO gear slot?

Well the job is done. Read below for how to info and avoid my mistakes. This is for an 8 speed 3000. Remove left footrest. Drain the rear axle to just below the PTO lever cover, about 3 gallons should do. I believe the manual says to engage the PTO lever (move to rear), then remove cover bolts, paying attention to different bolt sizes. There is a clutch pedal spring and bracket you'll have to fiddle with, not too hard. I put a drain pan under my cover. Remove cover with lever straight out, making sure shift fork doesn't slide off and fall into the sump. Note where a check ball sits under the back side of the lever and be sure you put the lever back so the ball is in the same hole. As you remove the cotter and roll pin to pull the lever off, make sure the ball doesn't go flying out or you'll lose the ball. Ask me how I know. After I got back from the dealership with my new check ball, gasket and o-ring, I put the check ball back on the spring and put the lever so the ball was in the same hole I started with. I advise working inside a box with the assembly as it's very easy for the ball to fly out. Squeeze the assembly together, oil up your new oring and put it on the outside of the shaft,press oring down into the groove, then hold shaft on with a temporary bolt. Now drive the roll pin back in and put in a cotter pin. Put gasket onto cover, orient shift fork with curved side down, and slip cover back on. If you have lever/check ball in its original position the shift fork should slip right into the gear slot. Start the top bolt, then fiddle with the bracket and clutch spring to get other bolts hand tight. Now check that PTO lever moves ok, engage it and make sure PTO shaft locks up and frees up with lever position. Now torque all bolts to spec, top off oil, run lift up and down a few times. A final note, if you're only changing the oring, you may be able to leave the cover on and dig out the oring after sliding off the lever, but I don't know if the lever will push back on without the shaft falling into sump.