My 300D does not have outside tire wear like you mention.

I did have to replace the idler arm (?) 2 years ago in order to get a front end alighnment.

Sounds like some front end part is worn.
How is the steering box??

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1979 300D 220 K miles
1995 C280 109 K miles
1992 Cadillac Eldorado Touring Coupe 57K miles SOLD
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1979 240D 140Kmiles (bought for parents) *SOLD.
SAN FRANCISCO/(*San Diego)
1989 300SE 148 K miles *SOLD