I pulled the cluster and gave the speedo a spin and darned if it still worked, I pulled the insert out of the cable housing and the cable had self destructed. It was only less than 5 months old so I took it back to Kragens and they exchanged it. This time I pulled it apart and greased the cable, all it really had on it was some assembly lube.
I swapped my speedo and did the gauge inserts:
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Interestingly my speedo gauge had been replaced before, it had a date of 1971 on it.
However, even with the white inserts it was still hard to see through the yellowed plastic, it did help, but I wasn't happy with it yet:
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So I figured I was going to pry the plastic off the back of the bezel and pry it off the donor cluster and glue it to mine, but I found that they're just set against the bezel and the gauges and cover is what holds the plastic in. (It's also set against 6 foam pads that slide in and has a guide to keep it straight)
Now I like the result, clean and easy to read:
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I just reassembled it and took it for a short drive, the new speedo is a little jumpy at low speeds, but steadies around 50 and it seems to be more accurate than the old one so far.
This is the fourth speedometer cable in 2 years, I hope it's the last for a while.