Ford: '88 3910 Series II, '65 3000; '07 6530C Branson with FEL, 2020 LS MT225S. All Diesels
Not for an XJ but the principle is the same:
I made my 4". I originally made them for my Branson2400 but upon selling it I kept them. When I bought the MT225s they fit perfectly.
Used 2 pieces of 1/4" steel plate per side (4 total). I used the wheel for a pattern. Took them to a machine shop and had them made. I forget the cost but not all that much and I wanted a set of 4" spacers and couldn't find any www sellers of 4". I then took a couple of pieces of 8" diameter steel pipe 3 1/2" long to make the pair. A little welding, a little paint and presto.