Aftermarket Speedometer?

I'm looking to update all the gauges in my '67 P220 with something aftermarket, like Auto Meter. The only problem I'm running into is with the speedometer. Specifically, it seems like all the aftermarket mechanical speedos use a 5/8"-18 thread, but my wagon has what seems like a 5/8"-24 thread on the cable. I did a quick search for a thread adapter but no such luck. Does anyone have any recommendations or suggestions? Should I get a custom cable made? Could I convert to electric? Or would just fabing up a DIY adapter be the quickest way? Thanks.

Any old time speedo shop will be able to make you a cable with what ever ends you would like on it... If all else fails call Palo Alto Speedo (). I don't think they make cables but they do lots of custom work on gauage so they would know who in the area would make one for you...

Try They would be able to make up whatever you need.

Thanks for the replies. After doing more research I've decided that going with an electrical speedometer would be best due to future mods I have planned. I'll need to be able to recalibrate for different diameter tires as well as a different transmission. The setup would consist of a , , and most likely an .