So the trans I am rebuilding has the sensor in the tail housing, I would like to remove this and put the mechanism for the cable speedometer. I know I need the new housing and the mechanism, but will the 1991 shaft work with the mechanism or "mesh" with the plastic gear on the shaft?

1991 4l60 (700r4)

 

I just went through the same issue. But mine was 700r4 out of similar year fbird with vss. http://www.transmissioncenter.net/sp...__va.htm#700r4 and http://www.tciauto.com/tc/speedometer-gear-calculator/ for more info. If you need the 40+ driven gear, ebay has the housing+gear for around 40 bucks. The drive gear I got separately from ebay too. The 34-39 tooth housing is much cheaper.