Is A bill of sale all that we need or do we need the title s

Is A bill of sale all that we need or do we need the title signed also?...My husband was married before and the mobile home he acquired was in his wifes mom and stepdads name. She only stayed for a year after they bought it, then he and I married and we paid on it for 11 years. The ex inlaws now live in Utah and there son here in Louisiana had power of attorney over there affairs here. my husband and ex brother in law went to an attorney and had a bill of sale drawn up for my husband. Is this all we need and does it have to be registered at the courthouse like a vehicle?Or do we need the title signed. We have it as the address on the account was ours.