>And rebuilds every 25000 to 50000 hrs would annoy the hell out of me. >(I'm not sure of the rebuild hours for truck engines, but I know fixed >Cats are in this range or near it...) Gee, 50,000 HOURS.. That is over 5 1/2 years.. Continuous.. what a hassle. And what do they do.. Change the oil and filter?? ;-)