i found the extra long sensor kit on the instruction sheet : #169-9300 (169-9305)
the cheapest place i found one was from catseye online store for $10.98 plus s/h.

here is the link: http://www.shopcateye.com/products.p...%7B47%7Ds-Long

here is the link for the installation, parts are listed on the bottom of page 2:http://202.215.251.86/images/manual/ED300%20v1_E.pdf