TR2-6 chassis Cross Tube rear, (smaller of the two on TR2-4) with an outside diameter of 1¼” (31.75mm). This tube is supplied at least 1035mm long (the correct length for TR4A-6) and fits at the rear of the chassis passing through the two chassis rails to accommodate the rear spring shackles on TR2-4A live axle and the bumper supports on TR4A IRS-6.

The tube is prone to corroding hence the need for a spare part. 

If this full length tube is not required we supply a shorter tube as a repair part to fit between the chassis rails. See  part number RTR7024 below.

This part is listed on the following page of the website, where further information and background reading may be found.

This part appears on the following Triumph Catalogue Plates