husband retired, sign language interpreter, if we sell 10 acres and get large down payment could we qualify for a loan to build ?

That depends since there are many factors that go into a pre-approval. I would suggest speaking with a local loan officer, doing a full loan application ( only takes 15 to 30 minutes) and have them go over all of your available options with you. If you need a good source, look at the top right of this website under the Community tab and click Find a Lender. Best wishes, Sean