This is a spacer for a drive shaft on Dodge or Chevy vehicles with the 9-1/4" rear end that use a 3" x 3" square (4-1/4" BCD) driveshaft flange. It is designed to fit between the drive shaft and pinion or transfer case/transmission flanges to effectively extend a drive shaft as needed due to a suspension lift, transmission swap, etc.

The main OpenSCAD file is for the full spacer, can be made any height and can be modified for different bolt patterns and pilot ring sizes. You can import this file into FreeCAD and convert it to other CAD format like IGES if you want to use this with CNC or to send to a machine shop, local or on-line.

The Chevy1500 sketch shows the dimensions for the larger 3-3/16" bolt pattern with a larger pilot ring size.

The DodgeInsert.stl file will produce a 3D printed insert to adapt the available 1" tall spacer to fit the smaller diameter pilot ring on some models (3rd and 4th photos). A 1" tall, aluminum spacer, with hardware, is available from:
https://amzn.to/4jkPEHo

This insert can be used to adapt a small to large pilot ring, as is. Or you can machine off the raised ring on the aluminum spacer (5th photo), you then use the smaller pilot ring on the insert (6th photo). The pilot ring is used to center up the spacer between the flanges.

Bolts: 4 x 7/16 NC x 2-1/4 for 1" spacer. Typically they thread into the flange, so match the bolts to whatever your threads are.

More information:
https://www.4crawler.com/4x4/ForSale/DriveshaftSpacer.shtml#Dodge9.25

Best machined out of something like T6061 aluminum or mild steel. For a part like this, it would be best to 3D print a sample part, perhaps 3/8" - 1/2" tall and check the dimensions and fit with your flange. Once satisfied with the fit of the part, set up for your desired dimensions. If you need something like an IGES or STEP format file, you can import the OpenSCAD file into FreeCAD and export the desired format file. Send that off to an on-line machining service like Xometry.com, JLC3dp.com, ProtoLabs.com, eMachineShop.com, MFG.com or find a local machine shop and have the part made.