Well, the thread title is "hayrake" and you are looking for a fan belt for a TRACTOR which does NOT have a fan belt, as the fan is gear driven.
If this is a legitimate question, you must be looking for a GENERATOR belt.
Serial numbers B60,000 through B306599 use a DEERE #B1587R generator belt.
Serial numbers B306,600 and up use a DEERE #B2893R generator belt. I would think yours must be in this range.
BOTH should be readily available through your nearest DEERE dealer. IF they don"t have the one you need ask them to put it on the next stock order to arrive in a couple of days (IF you can wait) to save special-order freight.
Belt Section 4L
Effective Length 29.100 IN
Width 0.497 IN
Thickness 0.297 IN
Material Spec PREM
Belt Section 13A
Length 40.500 IN
Width 0.500 IN
Thickness 0.331 IN
Material Spec POLYE