I don't know. Maybe. I would have to recommend the Bosch glow plugs - sold right here on FastLane.
The next test you could do would be a current test. This requires a multimeter capable of measuring about 20 Amps of DC current. Most multimeters cannot do that, but I can point you toward one that is relatively inexpensive if you want to try it.
The idea is that all the glow plugs should draw similar current when tested through the multimeter with the car battery being the source. Typically this starts out around 15 Amps and settles down to maybe 8 amps when the glow plugs get hot.
Sometimes a bad one will not draw much current and will not heat properly. Something like 3 or 4 amps.