Im trying to change the front speaker in my 66 Chevelle. Any tips on how to do this? Also my tach doesnt always work. Sometimes it works like a charm and others it wont move at all any ideas on why that is? Any info would be appreciated thanks.

For the speaker, you need to remove a single bolt that mounts the speaker bracket to the firewall. That bracket is press fit onto the speaker magnet so the bracket and speaker will come out as a single unit. Note that the speaker wires are hard wired to the speaker. You will need to pull out the speaker wire plug from the back of the radio, then disconnect the power wire from that plug to completely free up the speaker/bracket/wire assembly.

Others with more experience need to chime in on the tach.