These are part of a parallel bar suspension kit for custom fabricated rear suspension on a hot rod, street rod or custom car. The four identical bars are the parallel bars for vertical movement and the shorter bar is the side to side locator bar also called the "panhard" bar. These are made by a number of companies. The setup shown in the URL is made by Progressive Automotive as mounted in a custom frame for 57 Chevy. The mounting brackets are missing from your set. These can be used in almost any custom application with the correct mounting brackets for frame and differential mounting. The "panhard" bar in your set has only one adjustable end making it necessary to remove it for an adjustment. That is the only difference in your setup compared to the pictures in the URL.

These are part of a parallel bar suspension kit for custom fabricated rear suspension on a hot rod, street rod or custom car. The four identical bars are the parallel bars for vertical movement and the shorter bar is the side to side locator bar also called the "panhard" bar. These are made by a number of companies. The setup shown in the URL is made by Progressive Automotive as mounted in a custom frame for 57 Chevy. The mounting brackets are missing from your set. These can be used in almost any custom application with the correct mounting brackets for frame and differential mounting. The "panhard" bar in your set has only one adjustable end making it necessary to remove it for an adjustment. That is the only difference in your setup compared to the pictures in the URL.

References:

https://www.progressiveautomotive.com/installations-kits-parts/rear-suspensio...