Buy a new, blank VIN plate and have your title number stamped into it, then beat it up a little to make it look old.
Legally, in most states, a vehicle cannot be sold, purchased, or possessed without a VIN number. If your local DMV folks wanted to be anal about it, they could technically impound the vehicle if no VIN plate is present and send it to the crusher.
Alternately, i've heard of some DMV guys just telling the owner to carve the number on the title into the firewall and that passes as a legit VIN.
My '46 1/2 ton was like that.. it had been assigned a number by the DMV, and somebody carved that number into the firewall right below the VIN plate using what looked like a pocket knife.
