Will the HF 39083 or Phase II series 100 QCTP bolt directly onto the 9x20 metal lathes?

        No it is not a direct bolt on accessory. These QCTP use a larger longer shaft than is equipped
        on the stock 9x lathes. It is possible is replace the stock 10 mm toolpost stud with a longer
        14mm stud. Even with doing this the original cross slide (topslide) is really too small for this
         toolpost. There is a height issue with mounting the 39083 on top of the compound slide
         shown in the picture below.
         Update: Different methods for attaching the 39083 to the 9x lathe. Click here
 
 

                Using 1/2" tooling and lowered all the way the 39083 is just above center shown with the live center.
                1/4" and 3/8" tooling would work but you would still need to add a new longer stud.
                 It would also be possible to mill down the compound slide to gain the needed clearance.
                 I chose to leave the compound as is and just build a new toolpost holder.
 

  How does a QCTP work ?

       The  Harbor Freight 39083 is a piston type QC tool post.  It has a lever that moves a piston in and out
       which in turn applies force to the back of the holder and locks it in place.
       There is also a nut on the top of the QCTP that  holds the QCTP body in place.
       This does not affect the lever that operates the piston.
       With the top nut tight  the lever  will  allow you to quickly change from one accessory to another
       as shown below:
 
 

    Which QCTP will bolt directly onto the 9x lathes without any modifications ?

                Any of the QCTP that will fit the 7x metal lathes will work on the 9x lathes.
                No modifications are needed except possibly  a longer toolpost shaft or a
                washer to take up space.
                Harbor Freight offers the model 42806  QCTP  that will fit the 9x lathe.
                Not as heavy as the 39083 but it will work.

                The The Little Machine Shop also offers a TS Engineering QCTP.
                The TS Engineering is now a direct bolt on for the 9x lathes
               Please note that these two models of QCTP are a lot smaller than the Series 100 QCTP.

               Here's a review of the TS Engineering QCTP mounted on the 9x lathe:Click here
 

 What all is included with the HF 39083 QCTP kit ?
 

   Is the Harbor Freight 39083 the same as the Phase II series 100 QCTP ?

                      Yes. The HF also offers the 1/2" drill chuck accessory.
 
 

   What advantage's does the QCTP have over the original 9x toolpost ?

                      The main advantage to a QCTP is that the tooling can be easily adjusted
                      to the correct height without having to use shims. You can also change from
                      one accessory to another in just a few seconds.
                      With the QCTP mounted directly to the cross slide (shown here)
                      It makes for a very sturdy toolpost. Important for knurling and parting
                      which applies a lot of force.
                      I still also use the original 9x toolpost mounted to the compound  a lot.
                      My cross slide has the 4 bolt clamp which is needed to prevent any flexing.