UPDATE: I had a lot of request to make the bearing ride LOWER ~2mm. So there is a new STL named "Ender_3_Pro_Tevo_Tornado_2mm_lower_body.stl" that does just that. Thanks to @Cornely_Cool for posting the SolidWorks files, so I didn't have to reinvent the wheel! Just updated 1-9-19 the "Universal 2mm shorter Tevo X Tensioner body.stl" will work on all machines with either center threaded piece and nut. It will fit the Ender 3/Pro screw loosely (metal screw in the T-slot on front), but the belt pressure holds the piece in place. The screw is just an alignment tool/helping hand. I hate confusing posts, so here: these 3 files will fit universally with as much clearance as possible:

Universal 2mm shorter Tevo X Tensioner body.stl

ender_3_pro_pro_tevo_tornado_x_tensioner_slider_misterguru_open_center.stl

ender_3_pro_tevo_tornado_x_tensioner_knob_misterguru.stl
The Ender 3 Pro and My Tevo Tornado both have the X carriage bracket slightly past the rail on the right. This is properly clearanced (and currently in-use) on my printers. It has a slim adjustment knob, open-ended. 2 versions of the slider/sled/puller - one with a too-sexy "landing bay" for your shuttle craft (nerded-out there!) and a plain, solid slider. Added shorter-belt main bodies (-1mm & -2mm) in case you have clearance issues (STL only). Do not remove your belt: place the bearing into the loop and push in from the top slot. My Ender likes -0.07 Horizontal Expansion (Cura) for accurate parts, but clearances should be good on any decent setup printer. Like my Y-axis tensioner, the threads are clearanced a little. It should print upright without supports - I use MG Chemicals PETG.

For my Ender 3 Pro Y Belt Tensioner https://www.thingiverse.com/thing:3268192 STL and STEP files are included on both

Ender 3 Pro 3D Models