New Member Needs Help with 1970 Fuel Line

[PatrickGMC70]

Hey everyone. I just bought a 1970 C1500 GMC 1/2 ton with a 350. The fuel tank was leaking, and the sending unit was bad, so I opted to replace them. However, I've now found that the previous owner(s) have made some modifications, and I have to change everything back.

The old set-up was a rubber hose connecting two hard lines:






The hacked up line - looks like 5/16" to me:



The new sending unit looks like this (I ordered the sending unit and tank from LMC):





Just under the cab, there is a full filter that doesn't look factory. You can see how it runs down from the cab:



So what I'm wondering is:

1) what size fitting is the adapter that goes in the sending unit? (the nut is 18mm - metric??)

2) are any of these rubber lines supposed to be there, or it is supposed to be a hard line straight from the tank to the pump?

I saw that inline tube sells a 2pc replacement line, but the picture isn't clear enough for me to tell what the original set up was. Also, they sell a 5/16" and a 3/8" line. Is there a reason to change this over to 3/8"?

Does anyone know where I can get a grommet to fill the hole in the floor where the fuel line goes through? I haven't seen it in any catalogs.

3) I assume that fuel filter is not stock - can anyone confirm this?


If anyone has pictures of what this is supposed to look like, I'd really appreciate them. I don't want to "make it work" - I want to make it right.



Sorry for all of the questions in one post, but I REALLY want to get this thing running asap. Thanks in advance for all of your help!