Bosch Part #: 0 280 142 103 (is it a bypass valve for turbo?)

[Arryn Milne]

Hi,
I found this Bosch part #: 0 280 142 103 in a junkyard in the engine bay of 
an NA '85 5000.  They threw it in with the other stuff I was buying.
Anyone know what it is?
Thanks,
Arryn