From what I can surmise, has that little orange water heating light on the panel.  It's a KDI20.  Friends here had one when their hosue was built in 1984.  They ran it into the ground.  got them to get a new wash arm support about 10 years or so ago.  finally had to replace the machine about 2 years ago at the most.

Thanks Brent.  I think that's what I meant to type.  (Old-tymers strikes again). 

Steve posted his input on the wrong thread, so I've copied and pasted it here. 

A little bit of both!

The machine in the picture is a "HOBART DESIGN" but is not the original design of the Hobart 21's. This is a later developed machine which used the large loop element that sat just above the tank bottom.By this point, only the Superba and Monterrey series had the sump heater. This machine can be an Imperial model or even the Custom model which had a pots and pan, normal, light/china and rinse and hold cycles.I had that machine and it was a KDC21D model which had the higher line features of the Imperial like the adjustable racks and the tank trim and China Guard.

All the original Hobart built models had the heating element in the sump and had a heating indicator light on the control panel. The unit in the picture shows the big loop element and lacks the light or so it would seem.

What is important is the fact that regardless if it was built by Hobart or Whirlpool(actually Emerson/ISE),it had the Hobart design which was probably the best pump you could ever have gotten. Once Whirlpool really took over, they fitted the design with their power module pump. Another great washing system. IMHO, the grinding system in that setup cannot hold a candle to the 21/22 Hobart pump/disposer unit but did have a larger soil collection chamber and gave great results too.

If you find a machine of that design in good condition, you will always be happy with it. The same would go for any newer KA of the standard tub size with the power module pump. They cant hold as many dishes, but will give good results.

Hi Ralph I am going to take issue with your statement that the 21-22 has a better grinder system than the WP built and designed Power Clean disposer system. While I think that the 21-22 pump is the best most rugged pump and motor that Hobart ever put in a home DW it still does not come close to effortlessly disposing of the food waste that the WP system does. With the WP you can litterly scrape the food off the plates into the bottom of the DW and have nothing left to clean up afterwards. I you try this with the KA you will have a mess left in the sump to deal with. The access for the food to get into the grinder is just not as good and you still have a slimly filter to get clogged and need cleaning. I have made a lot of money cleaning up KA DWs and never had to clean crap out of the WP design.

Maytags pump after around 1990 that advertised a built in disposer also did not come close to the WP system as a lot of food would get caught under the large plastic sump cover. And unlike KAs you had to get out your tools to clean it or it would just stay there until it rotted away.

Of all the hundreds of WP PC pumps I have worked on I have never removed even a thimble full of food residue from one. To me this makes the WP PC pump not only the best system ever put in a home DW but also the carefree and sanitary.  Sadly WP stopped building this design around March this year for Sears, I think we still have three left in the warehouse. If anyone wants a real DW with a 1/3 HP motor check the Sears outlet centers fast. Otherwise heaven help us all.

Hey John, that post above is actually from Steve.  I've never owned a WP Power Clean so am not in a position to comment on their disposer system vs. the 21 & 22 series.

Sorry about that Ralph I didn't read the beginning very well. You have not really lived until you have had a WP PC machine.