I am selling a home. The sewer was put in inm ths 60's there are no records and no easements 6 houses are connected it runs through everyone's back yards. Do I nned to get easements before I sell this house

The short answer is no.

It is not uncommon that multiple homes have the same sewer line before it goes into the city sewer line.

No, you do not have to get an easement before you sell your house.