The only way to really know would be to find the phone number or email address for the HR or Recruitment department in Hindustan Engineering and ask them. Now, what you don't want to do is to use the phone number or the email address from the email that you've received. Find these details from their website, JustDial, etc.
Without knowing specifically about Hindustan Engineering's recruitment procedures, I am fairly confident that no employer sells their employment application form. I'm not an HR or HR Law expert, but if I'm not wrong, it is specifically prohibited in one of the Central Government's Acts.
You've done the smart thing by posting this question on CiteHR. If you do contact Hindustan Engineering and get a reply from them, can you please come back and post it here for other people's benefit?
Take care and good luck!