25R76E is a 1976 model year 25 hp... Are you sure the final digit is a 5? Not sure of the significance of that digit.
Parts can be found by Googling BRP parts catalogs.
BRP is only good for looking stuff up, cant deal with them direct.....much better to have a look here at iboats or boats.net, usually cheaper too.....crowleymarine.com, marineengine.com and ishopmarine.com are all sites worth a look too.....