At our clubs tech session on Sat one of the techs pointed out a slight greyish are on my 87 300Ecoil(320K miles) and said that the coil had gotten hot at some point. He rec changing the coil. Is there a way to test it? Also when searching under coil I noted other than OE coils eg Jensen. Do I want/ need them and do they fit well?

I must have posted at a bad time. Any way to test the coil? I was told my coil has a grey discolored area from getting too hot/having too much resistance at one time. How do I see if I need to replace the coil? could the excess resistance come from having the plug gaps worn to 35 or 40 from 30?

Unless the coil is still running very hot, getting visibly distressed AND the car is not performing properly (eg. mis-fire, poor fuel economy, difficult starting, etc.), I would be reluctant to worry about it. I find that I can usually spend enough money replacing parts that definitely need to be replaced without worrying about any that maybe don't look quite right. I guess you need to look at what can happen if you don't replace it. I am in favour of replacing something that will cause damage or is dangerous if not replaced but all that can happen with your coil is that the car will stop.

__________________
107.023: 350SLC, 3-speed auto, icon gold, parchment MBtex (sold 2012 after 29 years ownership).
107.026: 500SLC, 4-speed auto, thistle green, green velour.
124.090: 300TE, 4-speed auto, arctic white, cream-beige MBtex.
201.028: 190E 2.3 Sportline, 5-speed manual, arctic white, blue leather.
201.028: 190E 2.3, 4-speed auto, blue-black, grey MBtex.
201.034: 190E 2.3-16, 5-speed manual, blue-black, black leather.

There is a way to test them with a VOM ,but I just unplug the coil wire leading to the center of the distribtor cap and hold the end of the coil wire about an inch or so away from a good ground with a pair of insulated pliers and have someone crank the engine over with the key on, a good coil will put out a strong arc to ground a weak coil will show a yellow weak spark.............
William Rogers.........