If you are lucky enough to find one of the HS Blackhawk motors there is a possibility to modify the old 9vdc screwdriver antenna to a 12vdc system. Jim has engineered the offset mount and extension to make this happen without too much work involved. First, I took some backup measurements of the existing 9vd motor and coil assy. It is about 6in. between the bottom of the motor to the bottom of the coil assy (or 5 3/4 from the mounting hole on the motor housing). There was a 1in. distance between the double nut and the top of the motor housing. The distance is important as you need to make sure there is coil contact while in the lowered position with the new 12vdc motor adapter. With the new motor put in with the longer extension the motor to coil was about 1in. too short. Releasing the two jamb nuts, I extended the distance to make up for the shortfall. (this took about 3 tries to get it right). Prior to integrating the new motor, I notice that there was old dry grease. Removing the motor mount adapter there was plenty more to clean up with isopropyl alcohol. I decided to go all the way into the motor gear box and indeed the old grease was very hard. I have had a lot of good results with Lubriplate lithium grease in the past so I applied a new coat to the gears, shaft and washers. I also marked the housing prior to taking things apart to make sure they get put back together the same way. Testing the motor assy was much quieter after the new lubrication. Inserted the completed coil and motor into the tube and lined up the two mounting holes. Installed the spring contact assy on the antenna top with conductive anti-seiz and bug shield. Installed the bottom mounting plug, again with anti-seiz. All done. Test was successful in both directions. Now if I can just find my 12vdc rocker switch for up/down control. As a wild hair, I did a little research online on the Pittman Gearhead DC motors in the GM9000 series. Maybe someone has already done this and can apply their research. The key to the above was the motor adapter that allowed the geared motor to be centered and the machined connection adapter from motor to the coil assy. I now have a HS-1800 12vdc antenna. Also before I installed the motor, I took the paint down to bare metal and used Dupli-color automotive primer and paint in rattle cans to bring the mounting bracket and antenna to the same color as the car. (Well kinda close). It takes about 5 days for the paint to cure before I can wax the outside. I will take some pic's once its all together and mounted.