I found a good deal on a local center section for sale. I currently have a 489 housing with a big yolk and will be changing to a 741 housing that currently has a small yolk. My question is:

1.) Will the 741 housing bolt in place of the 489 housing or will I need extra parts?
2.) Will the yolk from the 489 housing bolt right onto the 741 housing in place of the small yolk?

Thanks!

Yes, center sections will swap, you will need a gasket though. Not sure about yokes though, IIRC, the diff is spline count for yokes, not housing number.

If all else fails, they make a conversion U joint to hook a small joint D/D to a big joint yoke, or vice versa.

The center section will interchange with what you have. I am not certain on the yoke, but they make U-joints that have both sizes on them. You can use the larger end in your driveline, and the smaller side to fit your yoke.

Both the 489 and the 741 came with either 10-spline pinions or 29-spline pinions, the 10-spline will have a 1 1/8" hex nut, the 29-spline will have a 1 1/4" nut.