Rallye odometer gear issue

I just got around to breaking down my dash in my 1970 Dart Swinger 340. Apon testing some of the gauges I realized my speedometer didn't turn more than 1/4 to 1/2 an inch. Once I removed the speedometer and had a closer look at it I saw that the small 1" (or so) odometer gear was snapped causing the spinning portion of the speedometer to catch. I've been looking around online and can't seem to find this small plastic piece anywhere. I haven't seen any posts about it in any forms anywhere and haven't been able to find one on any website. Its a small plastic piece that runs off the input shaft and goes to the gears for the odometer and trip. Has anyone had this problem or know what exactly this part is and/or how I can aquire a new one? I'll post some pictures as soon as possible. Thanks