I think the 489 center section with the crush sleeve elminator kit should be stronger than the 742?
My gripe is I priced out the cost of doing all the upgrades (yoke, gears, caps, spool, bearings, axles, and backbrace) and it was near the same cost as a new S60 rearend (and I could use my stock 8-3/4 in a different car anyhow.)