Going tomorrow to pick up the rebuilt generator for the 424 diesel tractor and now I'll be able to further diagnose the charging system per JohnT's directions. I'm predicting that the VR will not be working but hopefully it will be ok. I noticed that the Voltage Regulator is much larger in size on this tractor than say one from a Farmall 140 like I usually work on. Is that just because it is a heavier duty VR? Reason I ask is because I have a new VR for a 140 and didn't know if I could replace it with that one if its bad. OR....should I try and get an even equivalent to the one on it ......OR if it's bad can I repair the original Delco Remy one on it? The tractor has the factory charging system on it (12 volt generator negative ground, just like on a Farmall 140).