I had an 802A for a while and sold it. I have another right now 100% torn down for resotarion to like new. I had to replace the head gasket so I thought why not?
In general they are really great machines. Top shelf Onan generator and current production Lister Petter OPW engines. The LP design was licensed to Onan and Onan makes it 100% interchangeable with LP. Onan sold an enclosed civilian model too. So Parts are available from multiple sources including onan and Lister Petter.
They don't have the overload that the 002 has but they are very quiet, civilized and have a nice panel and a big diagnostic plug that can be used with just a meter to identify a variety of circuits.
The fuel tanks frequently leak at the remote drain connection. This is a major headache to fix as the tank does not come out easily. I now plastic weld that hole shut because the fuel is readily drained by siphoning.
The cooling systems are subject to need radiator caps replaced and head gaskets can be a problem. When you look at a unit or photos look for sign of white coolant tracking at the head joint on the starter side. You will be surprised at how many show it. But that issue is easily fixed. In fact the head gasket I just replaced was fine. The military fixed it but did not clean up the mess. The replacement head gaskets are updated. No further issues expected.
The fuel system is ultra reliable but is a challenge to synchronize the individual injection pumps. I do it by reading exhaust temps on the manifold legs, get it close and call it a day.
Personally, I really like this model. It is so high quality. Of this series of generators the 802A and 803A are the only ones with 100% aluminum skid and enclosure. The bigger 800 series ones use steel and it rusts in coastal environment. These are also EMP proof according to the military, if that matters to you.
The parts are pricey because they are not yet in mainstream circulation. they are current inventory until 2017.
I don't think any owner regrets having one.
Auction prices are $1,300 to $2,200 for the 802 and $1750 to $2,800 for the 803. Condition is everything and there are plenty being dumped because they are beat up and worn out. But some truely like new ones exist too. Just know what your getting.
Oh, the Lister petter is a 9000+ hour engine. Reports of over 20,000 hours when not fully loaded 100% of the time and not used in severe environments. Lots of info on the OPW. Been in production since the early 80's and well refined. The 802/03 military ones seem to start around early 90's and go on up. I have seen an '07 and '08 at auction.
I have not seen one yet that has signs of wet stacking. So they may be very resistant to it. Wet Stacking is a condition whereby a lightly loaded water cooled diesel will loose the hone pattern on the cylinder, rings quit seating and pump oil in a black sooty tar like substance out the exhaust. The older watercooled 004, 005, with the Hercules engines were very suseptable to this.