I see older threads recommending Motorcraft Beru glow plugs. Just though I'd check to see if 12 years later that's still true.
Noting your other post on the FTE Alternator sizing... I can only comment on my experiences with my '85 wrt BERU spade plugs. Noting my observational only experiences with several kinds of the Spade Plugs - paying attention to the source/origin/quality of GPs is absolutely necessary.
I have noted in various threads my vast troubles with the GP system in my '85 - particularly my frustration with remediation of a broken off tip... which turned out to be one of the fake motorcraft plugs. $1000 lesson.
My learning from all that was two fold: Bench Test your plugs, or at least verify them in place as yearly maint. And verify they are the right OEM plugs before you put them in. I don't think it matters which generation they are... this is what I do now...
My '97 - I'm going to have to get the meter out, as everyone did in the FTE Alt sizing post - and figure out what actually happens. Particularly since it has "chipset tuning". For everyone else - why this is important - would necessitate
deep reading this FTE post
In that long FTE Alternator sizing post you bumped - there is a fair amount of information woven in about the make up of the various generations of BERU plugs and the relationship to the other components... Everyone can make up their own minds about how important it is to them - mine is that those components are matched to provide an overall "engineering tolerance" for failure (a technical term in extreme scale computing systems) - and as a result prudent risk avoidance would include using OEM plugs - or a really thorough understanding of why you don't need to...