If you want your '77-'79 240D-300D to start this winter...
 

Yes I live in California where the sun always shines ...bla bla, But my '77 240 was getting hard to start last winter. I can see night time temps down into the teens. My '77 240 had the series type, Take 2 minutes to heat, loop glow plugs. I just put in the large thread bore, PENCIL type glows and WHAT a difference. I made up my own jumper wires to convert them from series connection to parallel. DON"T re attach the ground that is anchored at the front of the head.
I also used these in a well worn 300D that would give starting trouble even when the weather was HOT! The car started like new. (And yes, the old glow plugs were working)
I self time them now 5 to 10 seconds and she fires up perfectly! No need for the relay and kit.

Here is the BOSCH number for the glow plugs themselves.

Bosch LARGE bore, Pencil type glow plug: BOSCH# 0 250 201 044

PHIL has them.

You searched for: 0 250 201 044
Select Part Number Catalog Description List Price Your Price
Bosch Glow Plug $25.45 $17.39