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Old 08-15-2019, 03:12 PM   #1
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Location: West Jordan, UT
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Transmission Part Identification

We're working on a 1972 C10, 402ci engine on a truck we bought that was already torn down.

We have this "bell" looking thing hanging off the transmission and I can't find an image to show me what it is, or where it should be connected.

The identified connector, in yellow below, is a few inches away from another pipe (red) that that looks like it connects into the engine block, or so my daughter/helper said. The red pipe runs perpendicular to the "bell" but starts at the same height. I can't find the connections on a 1970 we have in the backyard as reference, the bell thing is missing...

I'll try to get actual pics up when I get home, but I'm scratching my head on if that pipe should be connected to the yellow bell thing, I didn't think transmission fluid went up to the engine.

I borrowed this image from another post, so I can't take credit for how clean the tranny looks.

Thanks in advance!
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Old 08-15-2019, 04:25 PM   #2
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Re: Transmission Part Identification

Hey look!
A vacuum modulator!

The pipe is the dip stick. Shows you the fluid level in the trans.
If your helper is talking about a small metal tube (1/4 inch) that runs close to the red one, that would be the vacuum line from the intake. Modulator needs full time manifold vacuum.

Look on the other truck again. The modulator might be on the back pointing rearward. It’s a turbo 350 if it is.
The trans in your pic is a turbo 400.
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Old 08-15-2019, 05:31 PM   #3
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Re: Transmission Part Identification

This picture may help. It's on a 350 engine, but I would think the bell housing
attachment point for the dip stick tube and modulator line would be the same on a big block.
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Old 08-15-2019, 09:39 PM   #4
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Re: Transmission Part Identification

The red thing is a hard line that vacuum signal from the intake manifold to the vacuum modulator (circled in yellow). You’d should have a bracket that attaches under the top right bell housing bolt. You will also need small lengths of vacuum hose to connect both ends of the hard line.
1969 C10 Suburban Custom (Factory 396/TH400, survivor with no rust)
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Old 08-16-2019, 09:17 PM   #5
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Re: Transmission Part Identification

Thank you all for the help, it was the vacuum line. It's connected and now off to the next educational opportunity of learning. thank you all!
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