Equivalent to these other universal replacement #'s:
Astatic N563 816 2906 AA253 P-108215 M77X 533 W117 
Once you have a visual or part number match, choose your tip/speed option suffix carefully. For details, go to Flip Needles FAQ .

NOTE: the "643" is the "guts" of the 644 needle assembly.  So a  handy/skilled end-user could re-use the handle of their 644 by installing this 643 assembly and save some money.