Does any body know what bag they used?

[71'tahoe]

I remember a company used to install a rolling sleeve bag in place of the coil springs in the rear of the trailing arm trucks and burbans. I dont remember the company name but remember them install the large bag in the rear. If memory serves me correctly there was a write up on the install in one of the classic truck rags or Truckin rag. I dont remember which. Any ways Im looking to do the same but need some kinda demension or part number. If any one could help it would be appreciated. O and by the way..I did a search and couldnt find what I was looing for as to most finds were of the frame laying kind of rear bags...