If it were me and I were doing it on a budget, I would simply use the bushings and screw in some pin type plugs, then wire them in parallel to a Ford starter relay using the bar type fuse and holder in the circuit. Then buy a 123 window switch and put it in one of the blank switch positions on the dash to energize the relay.

I did this before and it worked out very well and cost little more than nothing.

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2001 SLK 320 six speed manual
2014 Porsche Cayenne six speed manual

Annoy a Liberal, Read the Constitution

You need to test your plugs to see if they are all operational. A single bad glow plug will make for hard starts. The ohm test is the simplest. Unplug the harness from the relay and ohm out each plug/wire with a multimeter. Should read 1ohm or less.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13