I didn't call. I just ordered up some parts from them. Showed up two days later, no issues. The packaging looked like a Mom and Pop operation. I have no complaints with them.
I had to get a 19 tooth drive gear with a 36 tooth driven gear. I also needed the driven gear housing and bracket to bolt it down. I need all that to plug the hole on my 4L60 tailshaft housing, drive a vehicle speed sensor AND drive a speedometer. Not complicated at all................
I know your application is different but I've been researching a lot of speedometer stuff lately. I can't remember coming across any early stuff.
