A568 differential into A523

OK transmission gurus, I have a low-mile A523 with a .377 ratio and a differential from an A568. Can I swap the ring gear over and use the 568 diff in the 523 case? If not, why not?

Here is a few reasons. The bolt pattern for the ring gears are different, and the pinion gears tooth count and pitch are not compatible so you would have to change out the intermediate shaft as well. Then there is bearing size differences, then speed gears are different which require input shaft change out. Sort of a snowball effect. It would be real easy if it were just changing out the ring gear.
In order to change out what you want to do is use the entire 568 diff (including ring gear), use the intermediate shaft from 568 and put the speed gears from the 523 on the intermediate shaft. That way you don't have to change out the input shaft.
IMO, just use the 523. Since it is a 3.77:1 FD (92+), it is thought to be almost as strong as the 568. I believe Chris at TU was making some new LSD to fit those a523's and 543 (V6 bellhousing). "Edit" Well not so fast, it looks like they are sold out and maybe not going to be reordered as of 11/20. I thought I heard someone else say OBX was making LSD's again for 420a trannies? That may or may not be accurate, just hearsay.
Todd

Todd pretty much nailed it. Just use the 3.77FD 523 and be done with it.

To add to this, I recently found out that the minimum buy for Quaife has increased as well. Just a FYI...

The 568 ring gear is part of the differential case and does not come off like a typical ring gear would. It’s the same as the 555. You would need the ring gear from another 523 or 543.
If you do as Todd suggests and swap the corse cut 568 gears onto the 523 intermediate shaft you’ll have a stringer transmission. The hardest part to find for those are the fiber synchro rings, but as long as the trans wasn’t run with the wrong oil, those should be OK.