Don't know the year but an SAE 400 is an excellent heavy duty welder. It does have a couple set backs though. The 6 cylinder gas engine will be very thristy. If you want to burn 1/4" rods all day long or gouge at up to 500 amps, an SAE 400 is the machine of choice, however, if you wanted to burn 3/32" or smaller rods on thin material, you'd could have problems because an SAE 400 only goes as low as 80 amps. If an SAE 400 was used at near maximum and did a lot of heavy gouging, they can burn out. A lot of shops use electric driven SAE 400's as their dedicated machines for gouging. They were made for decades and old ones can often be found for next to nothing. If one burns up, they just look for another one. Lincoln still makes diesel drive SAE 400's. They even have a special model with stainless steel hood and extra corrosion protection for shipyards and other high humidity locations.
To answer your question, yes, they are a good machine but for a farm/hobby type machine doing all types of lighter duty welding, they aren't the best choice. They also weigh over 2000 lbs.