Thanks again for your input and the correction if my thinking is way off base, i do appreciate the feedback. It appears i should have reworded the original question a little. I am new to posting questions and put down an idea that may have not been totally accurate. Question should have sounded more "if" than "Reality" as you say, and not past tense. I tried to use basic details for the situation to figure best outcome, more details may be needed but the general idea still is as follows:

1. Client owns three business; 2 S-corps and 1- LLC (schedule E).
2. Client originally purchased new truck for LLC.
3. What is the best way to allocate/truck in operations?
   a. Client owns several other personal use vehicles.
   b. One S-Corp does have vehicle, however, vehicle is to be sold; as it is not being used enough (new
        detail)
   c. Client had idea of spreading out new vehicle among all business and wants to know how that would
      work.

Your comment

    "Why would someone buy a new Truck and then let it sit around and not be used, when that is why they
      bought that vehicle?"

Not sure what you mean. Lets go with truck was solely purchased for 100% use in the LLC, Even if its not used much is irrelevant, its a business vehicle. There are other vehicles for personal and currently one S-corp (new detail).

     "And you think there is a tax regulation that makes this advantageous?"

In short, yes. Our tax Regs most certainly give us some flexibility in legally setting up or choosing different aspects that provide the largest benefit for the taxpayer. Standard vs actual expense; choice of entity; accrual vs. cash, Lifo or Fifo;...having corporation reimburse owner/employee for business use of personal vehicle via accountable plan to name a few. It appears this situation would be no different.  The general question should be broken down into the two main points:

1. Should the new truck be used 100% for LLC and other personal vehicle be used for S-corp use
        (reimbursed via accountable plan).
2. Should the new truck be mix use among all; S-corps, LLC, "personal"

Of the two points, which provides the greatest legal benefit?

If i am drastically missing the point and am blatantly overlooking something please advise, i value input and not scared to admit when i am wrong, that why i posted in the first place. Thank you again for looking at my question!