A tubing hanger body made from Non-CRA steel coupled to production tubing made from CRA material. The coupling includes pin threads at the top end of the production tubing which are arranged to be screwed into box threads of the tubing hanger body. A seal sub having metal-to-metal and/or elastomeric seals engages the top end of the production tubing and protects the tubing hanger body from contact with production fluid flowing from the production tubing below to a Christmas tree tubing above. The invention includes a method of repairing of an existing tubing hanger body where its through bore has been damaged. This allows the through bore to be over machined and a CRA sleeve installed to replace tubing threads and body material.