Check out the New Holland parts page here:http://partstore.agriculture.newholland.com/us/parts-search.html#epc::mr60774ar989609
It shows 2 slightly different idler pulley setups in the picture, but it looks like the the part numbers have been superseded over time so that they're the same part numbers now.
The pulley by itself is part number 83958792 and the bearing is part number 83929142. Or you can get the entire bracket assembly with the pulley and everything else already on it as part number 83986807.
Good news is that they are all showing as in stock at partspring.com, so you should be able to get them at any New Holland dealer as well. The pulley by itself is $32.50 and the bearing is $54.83, while the entire bracket and pulley assembly is a whopping $225.01 (why the 1 cent???)