You can source them from Tyga directly
https://tyga-performance.com/advanced_search_result.php?keywords=TPER-5007

Or from Tyga in Europe
https://tygaeurope.com/product/crankshaft-seal-centre-mc16-and-mc18-r2j-r4j-2/?srsltid=AfmBOoptL-3OjvNyNmTXBdC2IvygWlQRbFIeDBUSFOaLPGf77QvFX8Ce

The crankshaft will need to be pressed apart and back together by someone who knows what they are doing. It would be wise to consider replacing the bearings as well while its apart.