Not that stupid.....stupid would be, "Will the ABS 91 XJ Dana 30 shafts fit in my 90 Bronco II?"
Yes, the difference is going to be that the ABS shafts have a tone ring, which you can ignore in your non-ABS XJ D30. FWIW, the Spicer 5-760x joint replaces the 297x unit, 760 is stronger and...