I am 3rd year student of polytechnic. Can I apply for MHTCET after completing Diploma in engineering?

With 63.57% in MHT CET, you do have a fair chance to get B.Tech in Fashion Technology at D.K.T.E. Institute, especially if you're in a reserved category or from the home state. Fill it in your CAP options and keep backup colleges too, just in case the cutoffs go higher this year.

To suggest colleges during MHT CET option filling, I need your CAP/CET rank and category (e.g. General, EWS, OBC). Cut off ranks vary significantly:

• COEP Pune (CSE): closing ~600–700  
• VJTI Mumbai (CSE): closing ~300–400  
• PICT Pune (CSE): closing ~1200–1500  
• Walchand College, Sangli (CSE): around 2588–3046  

After attempting JEE mains, you can pursue the course what do you want and attending JEE counselling, you may get college based on your arrangement of order in counselling 

With an 89 percentile in MHT CET, you have a good chance of getting into several B.Tech colleges in Maharashtra for the OBC category. Some of the well-regarded colleges where you might find seats available include Vidyalankar Institute of Technology, Atharva College of Engineering, Shah and Anchor College of Engineering, and others. For more specific branch recommendations, you can explore colleges like Ramrao Adik Institute of Technology, Don Bosco Institute of Technology, and St. Francis Institute of Technology.