>I want all of webprddt6.drawmextc1
>
>and only webprddt6.drawmextc3 Where recseq matches filter

Move the filter condition from WHERE to JOIN

  Left Join webprddt6.drawmextc3 On webprddt6.drawmextc3.codeid = webprddt6.drawmextc1.clcode
    AND (recseq = 52632 Or recseq is NULL)