Looking for Chenbro NR40700 short rails

I have two Chenbro NR40700’s. One of them has the correct length of rails. The other one, the server rail attachment part, seems to be a longer version. (Or I cant figure out HOW to get it smaller). So I am looking for someone who has this smaller rails, and is willing to sell. But even if you are NOT willing to sell, please let me know I am right about the different rail versions.

www.chenbro.com/en-global/products/RackmountChassis/4U_Chassis/NR40700

Rail length is determined by rack depth, shorter racks are usually like 20" deep

Measure the rack the rails are going in an order accordingly