The box type shown is one type, another is 2 pulleys close located on a mounting post such as
http://shop.raphaelsewing.com/index....roducts_id=354 The post mount can be had on ebay as low as $125US while the box type is $220US, but the box type has the advantage of mounting to the table using the standard 3 hole pattern and having the same pattern to remount the motor to instead of requiring you to plan and adapt your motor mount.
Have you had any luck yet finding manuals for your sewing machine? One forum suggests that there are manuals available for the LS2-1130 which they claim is similar.