psst... don't tell anybody, but it was straight in the Sync workup.
P.S. It turns out that 355 synced with 600.
04/09/2021,003,600 | 04/20/2020,600,433 | 02/10/1999,600,682
04/10/2021,846,149 | 04/21/2020,097,855 | 02/11/1999,399,434
04/11/2021,952,101 | 04/22/2020,142,896 | 02/12/1999,159,124
04/12/2021,696,306 | 04/23/2020,227,087 | 02/13/1999,581,325
04/13/2021,652,973 | 04/24/2020,246,028 | 02/15/1999,474,471
04/14/2021,045,604 | 04/25/2020,032,851 | 02/16/1999,242,756
04/15/2021,001,233 | 04/26/2020,244,016 | 02/17/1999,600,998
04/16/2021,687,142 | 04/27/2020,267,426 | 02/18/1999,595,537
04/17/2021,349,258 | 04/28/2020,806,186 | 02/19/1999,780,549
04/18/2021,990,182 | 04/29/2020,012,711 | 02/20/1999,940,415
04/19/2021,000,182 | 04/30/2020,384,043 | 02/22/1999,893,632
04/20/2021,939,382 | 05/01/2020,524,372 | 02/23/1999,225,704
04/21/2021,489,508 | 05/02/2020,949,938 | 02/24/1999,146,680
04/22/2021,060,242 | 05/03/2020,710,621 | 02/25/1999,109,812
04/23/2021,816,079 | 05/04/2020,452,313 | 02/26/1999,146,995
04/24/2021,438,860 | 05/05/2020,681,151 | 02/27/1999,244,463
04/25/2021,970,282 | 05/06/2020,171,277 | 03/01/1999,677,935
04/26/2021,104,904 | 05/07/2020,858,518 | 03/02/1999,446,451
04/27/2021,284,910 | 05/08/2020,223,675 | 03/03/1999,693,817
04/28/2021,662,537 | 05/09/2020,692,646 | 03/04/1999,936,366
04/29/2021,592,997 | 05/10/2020,133,772 | 03/05/1999,919,397
04/30/2021,355,xxx | 05/11/2020,355,056 | 03/06/1999,355,378
That 2020 hit was the most-recent sync so that is a one-hop backcheck hit. Very nice all around!