First time buying from a individual seller vs buying from a dealer... I have the boat all registered, however, now for the trailer. Since the trailer is under 4000lbs do I need to just take in the Bill of Sale? Should I take the plate with old registration from previous owner? Just trying to get it all squared away before going. Cannot seem to get through to the tax office.

If the trailer is less than or equal to 4,000 lbs. gross weight you will need the bill of sale and registration receipt. You might have better luck emailing mvt@tarrantcounty.com