You will need to check with Tru Turn to get the correct thread spinner nut and get a Part # for the 2.50 Ultimate Spinner (no wide slots), it looks like you will need to email Tower with the part numbers, if you can use a 2.25 here's links, have fun, captb
JUNO RC
http://www.junorc.com/spinner.htm
Tru Turn
http://www.truturn.com/contact_us.htm