Actually, it sounds like the part that was "found" was the transmission vacuum control valve. The shut off valve would have a single, brown vacuum line attached.

The shut off actuator is located on the extreme rear of the injection pump. Cylindrical in shape, with a hose nipple pointing straight up.

https://www.bing.com/images/search?view=detailV2&ccid=q7k3Ns0i&id=9F442E65CFEF5461C834C98ACA706E2906E78066&thid=OIP.q7k3Ns0ibC2_MjUtSyj8wAHaGP&mediaurl=http%3a%2f%2fwww.peachparts.com%2fshopforum%2fattachments%2fdiesel-discussion%2f79848d1271647942-79-300sd-fuel-cut-off-solenoid-picture767b.jpg&exph=600&expw=712&q=om617+shut+off+valve&simid=608050377412315525&selectedIndex=14&ajaxhist=0

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