I'd rather have a solid axle because of the common issues with the ttb...
There will be at LEAST as many issues with such a substantial modification, even if you do it exactly right. A lift ALWAYS requires maintenance, and it makes alignments more difficult/expensive. But putting such a light-duty axle (it breaks under Jeeps) under such a HEAVY engine is just asking for it.
The D50IFS is stronger, and rides better, and works better on-road & off-. Yes, it requires maintenance, but it's easier/cheaper to do it right once and then drive a hundred thousand miles, than to keep messing with a SAS every 15Kmi (or less).
Do you know what the housing is made out of?
The left front & right are steel; the left rear is cast Iron.
The steel is, but I wouldn't risk it. That's a critical component of the suspension, steering, AND brakes; if it's done wrong, or if it's done right & fails again, you could kill yourself & a lot of other people. It will probably take less time & money to swap out the cracked part. And it will CERTAINLY take less time & money to go through the TTB now, replacing everything that's worn with the newest/best replacements, than to SAS it.
...swaping in a Dana 60 does that require less modification?
Installing a different suspension that the factory offered might be less work, and it's definitely safer. But it will still require the same level of maintenance as a lift because you can't rivet the parts in. You have to bolt it in, and such critical bolts have to be checked for tightness regularly.