Question for those of you with aftermarket speedometers

[bigblock73]

I need to find a 1" ID grommet for the speedometer cable as it passes thru the firewall. I no longer have the stock grommet, but because my new cable is a screw on type (instead of a slide on like factory), I don't think I would be able to get it thru the grommet anyhow bacause it is larger than the stock cable.

So...for those of you with non factory speedos, what did you do?

Or if nobody has done this, does anyone know where I can get a grommet for this? I already checked out all the local hardware stores, as well as a weatherstripping place nearby...no luck. So any suggestions you may have...I am all ears.

Thanks in advance.

PS Mike, I know you said you used your old one, but until I see a pic...I can't see how it is possible (without destroying the grommet).