The nut is 1 5/16". To change the seal remove the pitman arm and then
the c-clip with a pair of lock ring pliers. Put a drain under the box
and start the truck for one second. The seal should blow out. If it
doesn't, start the truck and turn steering wheel. The pressure should
blow it out. Install new one and the lock ring and then the arm. Refill
power steering fluid and you should be all set.
GOOD LUCK!!!
