I have never seen an 038 case that would accept the side tensioner. My 028 has a side tensioner, but I haven't seen an 038, of any variety, with the capability to have one.
One is just the later version 1125-640-1701. It has a side adjust hole 'cos it used on 34,26,24, 38, 44, 46 saws, but you can't get a side tensioner for it.