a person shall not buy, receive, possess, conceal, or aid in the concealment of stolen … money, goods, or property knowing or having reason to know or reason to believe that [it] is stolen.
Since the Strat is valued over $1000 it's a felony.
The law is written that if a reasonable person has reason to believe the item is stolen, then they can be convicted. The OP already admitted to thinking that it could be stolen. Thus, if it is, and the rightful owner sees this, the OP and his uncle are going to be easily convicted.
I'm not talking about the moral side of this, and personally I'm a little disgusted by some posts in here, just the legal aspect.