Here's a question...is it possible to put an idle-control knob on a car that didn't originally have it? I ask 'cause I saw a 300TD yesterday that, according to the rear badge, had a turbo, but had the control knob...and I was under the impression that only non-turbo 300D's had it (and maybe the 116 300SD's?)...

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2001 VW Jetta TDI, 5 speed, daily driver
1991 Ford F-350, work in progress
1984 Ford F-250 4x4, 6.9l turbo diesel, 5 speed manual
Previous oilburners: 1980 IH Scout, 1984 E-350, 1985 M-B 300D, 1979 M-B 300SD, 1983 M-B 300D
Spark-free since 1999