Sidebar of interest...... glow plugs arent the be-all, end-all, last word in starting a diesel engine.

Truck part shops sell small $5 camping size, propane style orange cannisters of diesel starting fluid, used in commercial rigs that have NO glow plugs. Just attach an ordinary propane torch head to the tank, open the valve and stick the tank with torch head facing down into the air intake manifold, then git inside and start the car.

Another interesting option that skips glow plugs entirely is manifold heaters. A series of heavy duty electric coils that get red hot at strartup in the manifold passages through which air travels, it heats the air instead of the fuel as regular glow plugs do.