From inside (document excerpt):
Illustrated 11ST MODEL NAME EAGER BEAVER@ 02 600016-03 600016-06 600016-07 600016-06 600016-11 600016-12 600016-13 600016-14 600016-15 600016-17 600016-20 600016-27 600123-02 600123-03 600123-04 600123-05 600123-06 600123-07 600123-08 600123-09 600123-10 McCULLOCH 100 SERIES 160S EAGER BEAVER EAGER BEAVER@ SUPER 16 MODEL NAME EAGER BEAVER@ SUPER 16 600124-04 600124-06 600124-09 12 12 12 Eager Beaver@ and McCulloch Chain Saw are identified by a modal number (In this instance 600016, 600123, or 600124) followed by a suffix number (02, 03,04, etc.).
Suffix numbers denote variations In parts or assembles used In the manufacture of this product. Part numbers Iletad In thla I.P.L. which haves circled number@ or numbers preceding the description, are used only on the modal or models identified by a circled number @ or numbers. Part number which have one or more dots (.) preceding their descriptions may be ordered Individually, but they are also included In the kit or assembly whose description begins directly above the dot(s). Part number(s) In title IPL which were not in the previous IPL covering these area, are Indicated by e dash (-) preceding the new pert number(s). The policy of McCulkrch Corporation is one of continual improvement in design, manufacturing and engineering advancement wherever poesibie to assure stiil finer power tools. Hence, specifications, equipment, colors, design and manufacturer’s suggested iist prices are subject to change without notice and McCuiioch Corporation resewes the right to make such changes without prior notification or obilgatlon to becirfil or supply backfit components for units previously shipped from the factory.