8 3/4 question

can you easily swap between the numbered chunks? ie can you easily swap a complete 489 on a car that has a complete 742 in it now? I am keeping my 742/3.91 but want a second chunk with something taller for the freeway like 742 or 489 with 3.23s in it.
Yes but you'll need to find out which pinion yoke you have. The 489s are usually large yokes as where the 742s sometimes are but normally are small yoke. That said, they do sell u joint that will let you adapt to either yoke just fine fine. Other that that, it's a direct swap