Rear Suspension Difference

[dave3156]

I recently purchased a 1969 parts truck and the trailing arms are different on the parts truck than on my 1970. Pictures are attached. The trailing arms on the 69 have an extra mount on the back and what look like helper springs which bolt to the outside of the frame. I have a performance setup (built 350)with 3:73 gears in my truck. Is there an advantage to the helper springs? Is it worth trading out my trailing arms (the ones on the parts truck are in real nice shape)to get the extra stiffness to the rearend?

[el curioso]

The Trailing arms are the same the only diffrence is that the ones that have the helper spring have an extra plate that can be removed or added its up to you. The part that you would need to transfer/add is the actuall Helper spring.