What is this dohinkey?

[wfojon]

Hi,
I've got a 70 C10 pretty much all original. It has the original 350 V8 and a TH350 trans.
I'm doing a tune up and noticed a metal can in the vacuum line from the carb to the distributer vac can. It has another vac line and a wire going to it. I have no idea what the purpose of this is but it does look factory. I'm probably going to not use it and go a straight hose carb to dist.
The reason I think it is factory is there is a prebent metal line from the carb to the box with hose connecter's.
Thanks for any ideas.
Jon

[geezer#99]

It’s a transmission vacuum switch.
Used to limit your vac advance until you’re in high gear. In a turbo 350 that would be in 3rd gear.
An early pollution device.
You can bypass it with a vac hose.

[wfojon]

Thanks, I figured it was something like that.
I'll remove it and run a new line.

[geezer#99]

Don’t throw it away.
Some restorers look for them.
They came on some chevelle, corvettes and Camaro’ s too.

[wfojon]

No worries there, I'm one of those guys who save everything. Never know when a trade will get you something money won't.