This purchase sounds like a great potential for disappointment. It would seem that you will drive the truck for the owner who is leased to an expedite carrier. If this is the case, we have to guess your situation because you are short on details. In my opinion, the price of the truck is not as much of the issue as the ways and means to get to the title. 104 weeks is a long time if the deal sours at any point along the way. My comments are based on conjecture and knowledge of more than one deal similar to this arrangement.
What if the owner loses his lease with the carrier?
What if the truck has a lien on it and the owner takes your $2000 per month but doesn't pay off the lien before the 104 weeks are up.
What if the truck needs a $15,000 repair while you are driving, who pays?
What if the truck is involved in an accident, who pays the repair deductable, the freight damage deductable, the Qualcomm damage deductable, the property damage deductable?
What if the truck is out of service for repairs for an extended period? Will you be able to make the $500 weekly payments?
What if you have a medical situation that keeps you off the road for an extended period?
Will you be keeping 100% of all monies earned by the truck during the 104 week operation.
Finally, You will have no leverage with the expedite carrier if this deal turns sour. The carrier's lease is with the truck owner, not you. You will not even have the assurance that the carrier will allow you to sign on a six year old truck when you finally get the title.
We hate to sound like sour grapes, but I believe that more of these deals fail than succeed.