What can I do if I want to publish my PhD thesis work as is, but my advisor wants months of additional work? I recently completed my PhD thesis with minor corrections and I presented most of the data in international conferences (posters and talks). Now I am focused on writing up the data for publication in a journal. 

For the publication, 2 of 3 supervisors want me to change the direction of the analysis from data driven to theory-driven which will take several months and still might be rejected. They say the data is publishable as it is but that they want to fit the data to a theory that they are pursuing for other research grants (i.e. independently from me), and it may (or may not) lead to a better cited paper. I want to try to publish the data as it is, because that is what is in my thesis, I have presented these results before and they fit with my career interest. 

I was wondering whether it is acceptable to push for publication how I want it, i.e. if we do not agree on this, who takes the lead decision? At the moment, I am in danger of not publishing this work because we cannot agree, but I don't feel this re-analysis is to do with the quality of my thesis work, and is more of a hidden agenda. My supervisors had involvement and that is not the issue. If I were still a PhD student, a re-analysis would likely happen (out of interest) but since I am a post-doc in another research group, I'm not keen on a re-analysis for the fun of it.
As usual, the first piece of advice I can offer is to talk to your graduate advisor to get his take. That said, it sounds like you're getting advice which will increase your chances of getting a paper accepted from people who have experience in the field.

Your theory that they're asking you to do work related to a "hidden agenda" seems a little far-fetched... when considering the extra analysis, writing it up, and publishing, you're looking probably 18 months into the future. Your committee is well aware of this. The likelihood of all that happening in any timeframe that would be beneficial to them is pretty darn small. Even more so, they have their own students who can work on their stuff. They wouldn't hang their hat on the chances that a graduate student who has already moved on will do some research that may or may not result in a publication. Long story short, I wouldn't worry too much about ulterior motives.