Hello blindman--  I can quickly send you to a site that will give you all the text, diagrams(click on the diagram for a full-size view) and pictures that you need to replace the heater core in your 1993 Chevy Lumina.  It is still hard work, but getting it done is better than trying to drive around all winter with no heat.  Go to--  http://autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/0e/d6/54/0900823d800ed654.jsp.  Let me know how you do.  I love fan mail.   Good luck from Bovan.