Thanks for all the reply's...I ended up using a 2 pronged strategy...I ordered some of the Critter repellant referenced in one of the earlier posts, they included a bunch of little nylon sleeves that you tie off one end, fill it and then tie off the other end and end up with a little golf ball sized nylon bag of their repellant...I ended up making about 20 of those balls and hanging them with zip ties at different places on the truck...4 or 5 in the engine compartment, two or three under the seats, two or three under the dash, one in the glove box, and one in the end of each of the exhaust pipes...has kind of a strong peppermint smell that supposedly all small animals and rodents do not like.
Also took 4 small Rubbermaid containers and punched 3-4 holes in the lid and put about 6-10 moth balls in each and put them under the four corners of the vehicle...finally took the "critter-away" stuff and sprinkled a perimeter all around the vehicle.
I'll let you know how it works next spring.