Hi,..... check out...... http://farmex.now.tc/catalog/index.php ..... look for Echo short blocks. Some are cheap some more expensive. You will have to know the number for your block or just surf through the list till you find what you are looking for. LOL

In your size range would be the sb-1055 for the cs-510 or Sb-1080 for the CS-520 saws. these are both beam mounted and have the carb flanges for a bolt on set-up. The price in the catalog is $190.00. I don't know your situation. These are the shortblocks Keith used for the BME 50s I am sure.