Difference is probably model year.
As far as telling whether it works or not, without a history, you will need to do a few things to keep it from possibly self destructing when powering up due to it's age and the possibility that it has never been worked on before. You can remove the bulbs and check them with a DVM.
1.) Take the chassis out of the case, take a picture of the topside, then flip it over, remove the bottom plate and take a fairly close pic ofthe bottom side. POST THE PICS. This will allow us who have seen them up close and personal to check for new parts.
2.) Visually inspect the inside (TOP), and make sure ALL the tubes are in the sockets, verify the tube nomenclature with the manual or diagram. If missing DO NOT POWER IT UP. If incorrect, there is the possibility that the tube has been replaced with a substitute. Check NJ7P's site (
http://www.nj7p.org/Tube.php ) and type in the substitution tube, or even the original type and look at the sub listing.
2.) You will need a "VARIAC" to bring the voltage up slowly, while watching the unit for arcing, sparking, or parts that smoke. 10-20 volts every 15 minutes or so. Watch the tubes for arcing internally. The lights will either come on or not. If not they are probably blown. Check the can caps, and transformers for abnormal heating when powering up. There will be some voltage checks you will need to do so you'll need a Digital Volt meter (harbor freight has a cheap one that works ok.). There are voltages (>300VDC and AC) that can kill. Be extremely careful. I'm not trying to scare you off, but you need to be aware of this. If the transformers get overly hot, shut it down and take it to a shop.
Do NOT just plug it in and fire it up until it's been checked and verified that it's ok to do so.
From the looks of it, by the pics, it looks like it probably would be ok, BUT WHY TAKE THE CHANCE and possibly ruin a good thing.
Larry
