I put a 2" finger track on my 03 and just used the 04 snopro brackets and it works well. I know the design is alot different on the M series brackets but that doesn't mean they won't work, where as the 04sp are just about a bolt (rivet) on I think you have to drill 2 holes. Another thing you might think about is the cost 04sp - $15, Mseries - $50 apiece.
Hope this helped