after you take your arms off the truck. you will see that the original spring cup is offset more to one side. all i did was take a 8 3/4 inch pipe (outer diameter) 1/4 inch thick , and layed it down over top the original spring cup pocket hole and centered it the best i could . i traced around the outside of the pipe with a soap stone. i cut the old pocket out and ground down the opening until the pipe fit in the hole. sunk the pipe 2 inches into the arm, then i capped the bottom with some .25 inch thick plate.
before i welded it all together. i test fit the re7 bag in the arm (on the truck) to see if anything was going to be off or have rubbing issues. everything lined up as it should, so i welded it up..
if i could go back and change anything on the arms. i would have used a larger diameter of pipe. around 9 3/4- 10 inches. i would have been able to use a re8. a re7 will work fine for what i need. (just to get the truck off the ground so i can roll.) the pipe i used was free. it was all i could afford at the time...