Andy, I assume the collector plate on the truck is very old, So have your sheriff buddy run the serial number through the stolen vehicle data bank. If it comes back clean, go the WI bonded title route.

See what you have to do to get a bonded title. In IL the truck has to be near road worthy (someone has to sign off it can be made safe to drive on the streets of IL) and has to have a whole sale value assessment (IL requires that from a licensed auto dealership), a surety bond (2x the assessed value, through an insurance co), and pictures, all submitted at the same time. Then it comes with a 3 year time frame someone with earlier dated proper paperwork can claim the truck. If the guy you bought the truck from really has had it for long enough for the collector plate to be out of the system, there shouldn't be anyone holding a title older then your submitted paperwork. Unless the previous owner's relative is actually holding an existing title, they won't be able to prove the truck belongs to them to get a lost title. Since the plate is no longer in the system, the title attached to the plate is no longer in the system. If the truck was ever reported as stolen, it should turn up in the stolen vehicle database unless an insurance company paid off for the stolen truck, at which point the truck would have belonged to the insurance co, and they won't be back to claim it, its been long written off. That is why the title bonding works and why its available in most states..

The WI process is probably different. You need to follow the WI process.