From my experience of building the sliders for the 73/74 series I have found out that there are a lot of differences between the various power sources and frames depending on light or heavy duty . The exhausts seem to run different enough between the variants to interfere with the fitment. When Jason build the original slider I was reproducing he build it for a BJ73 or BJ74 , that exact slider would not fit on a HZJ73 or a FJ73 without reworking it . For the 76/77 it will be easier as these are all 1HZ so the only difference would be crossmember location depending on automatic vs manual . On the troopies you probably have 3 different engine versions and the same amount of transmissions to deal with .
If customers show up with their cruisers to your shop it would be easy enough for you to get it perfect . Shipping them out welding at a die made for a slightly different model might be getting frustrated customers .
Both Trail Tailor and Metaltech have build 7x sliders in the past but stopped offering these , probably for the reasons I just mentioned .