I believe the S-18's shaft is/was too long and will interfere with the steering wheel, thus why the S-16 was used on ADs. It has a shorter shaft. The S-18 was seen more on sedans. At least this was what I learned some time ago on the net.


Craig

My '50 Chevy 3100 5 window, '62-235cu, 3:55 rear
My truck ....... Respect The Rust
If I'm not working on my truck, '65 m00stang or VW camper, I'm fishing with the wife or smoking Salmon.