Uca?

Was looking up UCA bushings to build some over the weekend. I hopen and noticed that there are 2 different UCA part numbers and 2 different UCA bushing part numbers. Are there 2 different UCA's in the XJ? The break was 84-90 and 91-00. Also, anyone know what the inside diamiter should be for the UCA bushing. And what size have you guys been useing to build arms out of? .25 think? Body side of course b/c the UCA does not have bushings on the axle side. They are on the axle! TIA