Pennsylvania Motorcycle Trade help

Hi Reddit,

I reached an agreement with a Craigslist seller to make a motorcycle trade. I will be trading my GS 500 for his SV 650. However I cannot find a law or recommendation on the paperwork to complete this trade? Are we technically a double buyer/seller that needs to pay a sales tax? Double gifters? I can't seem to find a clear answer and could use some help.

Thanks!!