Clearing your belongings through customs in Puerto Rico

Puerto Rico is a US Territory... there is no customs!

IMPORTING A CAR TO PR IN 10 EASY STEPS

While not technically a duty, cars have a 25% tax on entry to PR. I just did this. It was not as hard as I thought, but it took most of the day. Here was how it worked for me.
You can look up what PR thinks the value of the car is online.  Put in the VIN or the model and year and the system will give you a retail value they base the tax on.  Mine seemed very high.  From there:

1. I brought a local friend - highly recommended.
2. Got a notice from the shipper by e-mail that car had arrived in port and been cleared - they say clearance takes 1-3 days from arrival on the ship.  Mine cleared the same day.
3. Arrived at the port and went through security.  There is a small one-story building there.  I went to the first set of windows and gave them ID and documents supplied by the shipper.  They looked up the docs from their side and sent me around the corner to the tax office. 
4.  They checked the documents and my ID's.  THEY WANTED A SOCIAL SECURITY CARD as part of the ID.  I had been warned so I had it.  They give you a tax bill which you have to go into Old San Juan to pay.
5. You go to Hacienda which is in a large building in the Capital area of OSJ. There is an office there where you pay the bill.  You can do it in cash or with a credit card (Master or Visa).  I expected mine to be ~$8k and it turned out to be around $6.
6. I returned to the docks, Went to the original windows with the tax receipt and they released the car to me with temporary plates.  Got all this done in the morning as my friend knew where all these things were.
7.  You have a short time to get the car registered. YOU NEED TO GET THE CAR INSPECTED FIRST.  This is easy, they can do it at inspection stations attached to a good number of service stations and it only takes about 15 minutes.
8.  You then go to the DMV with all your papers.  The DMV lived up to their reputation all over the world, but I drove away all legal by the end of the day.
9.  Finally, bought a toll pass at the first toll plaza I went through. 
10. Affixed the stickers at home and DONE

Please try to be more precise, as it is difficult to follow your story. You said you expected the Hacienda bill for your car to be $8000 and it turned out to be $6000? Is that what you were trying to say?

Might I inquire, what is year, make and model of your car?

Yes.  The car was a Jeep Wrangler.

I have been following your advice, Rey, as I am moving to P.R. in the next few weeks. I am hoping you can shed light on the 55 gal. drum you mentioned for shipping. Is it an industrial steel drum? What type of top is required to lock it down? The ones at Home Depot are plastic and flimsy, with spigots. I am looking for a vendor with an 800 number, preferably, as Home Depot employees cannot help, and I need to be sure I buy the right one. I'm not even sure I can get it into my car for delivery to Rosa del Monte! I would appreciate your insight as I need to get started soon. Thank you.

OK. As an American relocating, do I understand correctly that I do not owe customs duties on possessions I bring in?

Is the car tax included in the fee charged by the Hacienda when the car comes off the ship?