My buddy came up with this modification when we were installing my Marlin lift kit left on my 82 pickup. We were welding the truck up and were pretty much done, all the remained were the rear shock tabs and the rear spring perches. He took on look at the perches and the amount of space between the perch and the axle itself and said he would not weld them. In order to get the perch properly welded, you have to lay down layer upon layer to fill the gap. It was around a half an inch in my case. He ended up cutting some 3inch sch40 pipe in half and we sleeved the axle, and the perches laid right on top, the pipe also laid right on the axle with very minor clearancing of the stock axle welds.
if you have done this mod on your own im pretty sure you have run into this issue, just wanted to pass the info along. My buddy was in hawaii so I had someone help me finish the alxe. Ended up bing Superyota, he liked the idea too. So I decided to share it. Superyota even thought of extending the bottom pipe accross towards the pumpkin, acting as a cheap strength gusset, which I will do in the future. Here are a few extra pics
I spoke with my buddy who came up with this, he said you should just have to weld the corners of the pipe, prob about an inch on each side. If I were using these as a gusset I would probably put in a few stitch welds along the long sides.