rodknock95
Blaze,
It would depend on if the Kirby cleaner you have has the original factory brush roll with sleeve bearings, or if it has the replacement brush roll with ball bearings.
The recommended belt for use on all models from the 513 up to the Dual Sanitronic 80 is part no. 159056S (3 belts) or 159056A (25 belts).
For models 505 to 512, which had the brush roll with two open ends, the original factory replacement belt was part no. 1590S (3 belts) or 1590A (25 belts), but that older-style belt had been discontinued years ago, so the 159056 belt is also recommended for these models as well.
For models from the Classic 1CR to the Legend II, if these have the original factory brush roll with sleeve bearings, the following two respective belts are recommended: 159056 (for Classic 1CR to Tradition 3CB) or 301289 (for Heritage I to Legend II). But if these same machines use the ball bearing-equipped brush roll with the color-coded end caps, use part no. 301291 (with the inside tread).
Roundup of belts to use:
1590 = 505 to 512 (original; discontinued - use 159056)
159056 = 513 to Dual Sanitronic 80, and Classic 1CR to Tradition 3CB if with original factory sleeve bearing-equipped brush roll
301289 = Heritage I to Legend II, if with original factory sleeve bearing-equipped brush roll
301291 = Classic 1CR to Legend II, if with new-style ball bearing-equipped brush roll
~Ben