It depends on the year also, earlier gen need a 3 blade pro (Centurion uses Aceme), later Avalanche use a slightly different transmission and a 4 blade pro - what year - I have a 2003 with a 3 blade
very important question is whether you have a reduction gear in your drive. The Fineline customer service rep.. Shelly? is always very helpful (call the merced number form their site). on centurioncrew.com you may find someone with your exact setup who can give some suggestions.