A search at the original manufacturer’s site (Chicago Rawhide, now SKF) crosses the 302495 seal to SKF 6280, which is available at places that sell seals – not marine dealers.
Here’s the lookup site:
http://www2.chicago-rawhide.com/popup_p … 457012.htm
Here’s where it takes you giving specs on the seal:
http://www.skfextranet.com/Catalogs/457 … asp?s=6280
and here is one of many places to place to buy them if you run a websearch on SKF 6280:
https://www.amazon.com/SKF-Small-CRWA5- … B002ERWYOC
Dave