David C Klasse
I had the same problem and went crazy looking for the cause. Replaced the front upper control arm bushings . Improved the ride but squeaking stayed.
Today I found out the problem its the lower ball joint on both side front. Rubber boot was cracked and so lube must have dried . Sprayed lithium grease with a thin nozzle in there. WOW problem gone no squeak at all. Now when I am ready I will replace those big budget lower ball joints. Ball joints are 16 bucks each bu labor is a killer about 350 to 400 bucks total.
One penny saved is three penny earned.
1985 300D Turbo 179,000miles