Hello. I own a 351 bar mower, and need to replace some parts. Long story I won't get into but  need  following pieces: knife head 504757E;  knife bearing block 504728ES ; 504749EW  is the bar ( I suspect I can make one of these from the other green work); and 504758E  head spring.  These numbers are from a 351 Cockshutt book, but I am confident they are the same as the Oliver. Appreciate any ideas, suggestions, or whatever from all with an idea. Thanks