David,

About 2 hours if I have to adjust all the valves. But most the time only a few or none have to be adjusted so much less time. I always measure the valve clearance before I loosen anything because most the time the clearance is OK. I adjust them every 25,000 miles. I know the manual says 15,000 miles but that is excessive on older broken in engines. I'm waiting to see if any of the valves need adjustment after 50,000 miles because none needed adjustment at 25,000 miles. I always set to the high side or the tolerance because the wear is that the clearance becomes less.

I never had any trouble with the valves turning. Maybe I'm just lucky.

Replace both filters as needed. When is it needed: When you notice a decrease in engine power on a hill. If you get clean fuel without any algae, the filters will last for almost ever. A new filter won't filter better than an old one: Just the opposite is true.

That's not cruise control equipment on the valve cover. Its EGR valve controls. A '79 300SD does not have the vacuum junk on the valve cover because there is no EGR valve, a big plus.

P E H