Yes you can use nylocs for the tca joint, but it may lock on tight enough to spin the joint bit that goes through the arm, but if you apply a little pressure from a jack undeneath this will stop it spinning so the nyloc can be tightened, if this doesn't work strip some wire and cut a few strand of copper wire and put in the hole before inserting the tca joint, this will hold it tight, allowing a nyloc to be used.
tabetha