Again, asking which one fits is pointless.
Put up some pictues of the machine, that might help a little.
I googled colt 5 7221 and all i get thats useful is a link to this thread.
Im pretty sure its a B section belt.
Get some 10mm rope and string that around the pulleys, mark the rope where the end comes too and measure the rope. That will get you an idea on the belt length.
I only see two belts for the colt cutter deck in the shop, one is 55" the other is 59"
Id say its the latter as the former is for a GT2000. But you would need to check it.
