I have had good luck with inserts for the 1/18 off road trucks. plus they were 2 bucks for 4. I used the hard inserts. I have read they info about the full size stuffing but have not tried it. something along the line of tapeing the dia downand stuffing and restuffing until it all lines up then glueing. it talks about the stuffing the full sized inserts on the tamiya ste op page for the m-03L