So I've determined that four of the glow plugs in my '85 300D are bad; one had a resistance of under an ohm, but the others ranged all the way up to some 1MOhm.
I go to AutoHausAZ to check things out, and they've got the Bosch "pencil type, for fastglow system" plugs. Performance Products has a picture that looks "loop type," and they're about $3 more than the AutoHausAZ ones.
Will the AutoHaus ones work in this car, if it's got a stock relay? For some reason I'm of the impression that the "loop type" went away during this model series but certainly I could be mistaken... The fuse in the box is 80A, if it matters. ...and I'm not certain that the relay is stock, but the fastglow kit makes me think there's a box for four cylinders and then "other stuff" somewhere else for the fifth...
thanks,
-tom!