Well Harry just out of curiosity can I ask you why do you want to do an MBA? I mean, you are doing your Masters degree and haven't even completed it, so if you now want an MBA too why didn't you do an MBA in the first place? Also i hope you are aware that the schools are definitely going to ask you this.

Well,
My long term plans are to set up a Polymer Industry catering to Automobile sector. As a cog of the long term plans -
I wanted to gain exposure and learn the nuances of how automobile industry works. So, I worked there for four years.
Then, I wanted to do a Master's (with Independent Research) in Polymer Engineering. That is the reason for Master's now.
MBA is the next step that would help me in shaping my overall skills apart from the technical knowledge.

Harry

Wow sounds like you were born with a game plan. Great to know about it, Harry.

Anyway to answer your question, although i'm not sure about the exactly GMAT intake scores of the schools you mentioned, i suggest you to check their average GMAT scores and their 80% intake GMAT range. This will give you an idea where you stand. If you are on the upper end then you are in a pretty good shape. If not your application needs to be strong enough to prompt them to want you.

Also note that, some schools allow you to arrange informational interviews and some allow you to send your resume and get feedback before you apply. some also allow you to contact them. Check out if this is a possibility. If so they are the best people to answer your question.

Now note that you are a unique applicant and GMAT is just one small part of the application. So if you can write some impressive essays and get some great recommendations then i dont think you would need to retake your gmat.

All the very best with you applications.