Please forgive me for a stupid question then, but whats the difference between a SR and a ST?  I'm sure its blindingly obvious but I've been doing all my research on listeroids.....

Can they also be run on just about any kind of oil?

Looking at youtube they're both pretty loud

Edit:  Also, where can I find one?

Hello from Tacoma WA.  I'd like to tap your collective knowledge and experience before I plunk down a large bit of my limited cash.

I need an absolutely reliable powerplant for backup power to be used for weeks or even months at a time as our only source of power.  It would have to be left with my extremely non-technicial and somewhat frail wife while I left for work each day.  It would be feeding a 1500AH battery bank via a grid-tied 4000w inverter/charger.

The most important thing is to provide power for my wifes 780 watt home peritoneal dialysis unit (her kidneys dont work) which is used 9 hours every night and MUST have reliable power, the unit will be plugged into the inverter/charger full time - basically turning the battery bank/inverter into a huge UPS for her.

We'll be moving into the outskirts of the Gig Harbor area, from all accounts from my coworkers who live out there power outages are frequent and long (up to 2 weeks).  
My plan is when the power is out I'll use a transfer switch to power the house from the inverter/charger and use the powerplant to charge the batteries.  I want to stay with a 120V charging system to use the pass-through capabilities of the inverter/charger.  I also plan to have a 100amp marine alternator as a backup power source.

Also, I'd like to do cogeneration of domestic hot water - I have a few ideas based around using a old gas-fired hot water heater.

I'm thinking my bet bet is to get a kit engine since I'd be tearing it down to learn/clean/desand it anyway and I'd save a few bucks.  I'm drawn to the heavy-metal engineering of the listeroids, the relatively quiet operation, durability and the ability to burn almost anything.  I'm also a bit of a disaster prepper and a listeriod would fall in perfectly with that.  I'm perfectly willing to drive up into lower British Columbia to pick one up if I have to - I've driven the AlCan highway 5 times now in my various moves to/from Alaska.

I'm a simulator technician at a full motion flight simulator and have been a tinkerer/DIYer all my life so I dont see any problems with the technicial aspects of the project.

So, what do you think ?