VEVOR K11-200 Lathe Chuck 8 Inch 3 Jaw,Self Centering Chuck Hardened Steel Jaws,Internal External Grinding for Lathe Drilling Milling Machine

Ok, there are several things to note. 1. Given that you state, that the Harbor Freight is 9"; the 8" chuck would fit 2. Chucks are usually threaded onto the lathe spindle. Typically, the chuck itself is adapted to the spindle with a plate that is bolted onto the back of the chuck. This plate is typically removable. 3. The 8" chuck advertised, does not come with that adapter plate. 4. Grizzly sells those adapter plates. You would need to know the thread size of your spindle. Either measure it or look on the lathe spec sheet. 5. I made my own. machining down a 5 lb cast iron dumbbell weight. Mine adapts the existing plate (already threaded) from my original chuck to the new chuck. That way I did not have to chase any threads. Hope that helps.

if it is the standard orange k 3 jaw it should be standard

This mini lathe chuck is composed of a chuck body, a movable chuck, and a claw drive. Because the chuck is self-centering and requires no calibration, installation is simple and quick. Internal Jaw Clamping Range (A-A1): 0.16" / 4 mm - 3.35" / 85 mm Internal Jaw Jamming Range (B-B1): 2.56" / 65 mm - 7.87" / 200 mm

for the 8" pilot dia should be 6.496 " bolt circle 7.086" the 10 " can also be found on the internet. but in any case i would not machine the back plate until you have the new chuck in hand.

NO, the chuck requires a back mount plate with a 7.09 inch bolt circle. Not sure if you could find such a plate as a production item. If you have a machinist friend that would make such an item, it could be done. Take into consideration your lathe spindle brgs as this unit weighs 30 LBS. plus the added weight of the adapter.