look up my first thread... you can see all the straps, c-clamp and crap the guy wrapped around the block and ubolts, because he spit a block out going down the road. he fixed it, but was worried it would happen again. anything beyond the stock block size is dangerous and even that was a **** poor substitute for proper springs. think of a block as a prybar... how big of a prybar do you want trying to rip apart your rear suspension while driving?

granted in my case they were 6" blocks, 35's and a welded diff on dry pavement... bit extreme, but it can and does happen. i thought it was an old wives tale too, till i got this truck. i could feel everything trying to rip apart turning the thing before i fixed it.
the u-bolts were plenty tight... nice BANG when i cut them off.

 

Kinda like the axioms "never re-use u-bolts" and "all plenums leak"? Yeah, not in my world. The only absolute is there are no absolutes. But I'm glad you feel safe now.

 

These "weak" engines cause a pretty good but if axle wrap. Look up ram technologies on YouTube. He has a video on a 2nd gen 2500 360 and you can clearly see the axle wrap

 

My daughter's boyfriend bought a 2500 with stacked blocks. They were loose and he tightened them before they came out. He finally put a shackle flip kit from DIY 4x4 in it with a single block. That's what I would suggest you do. Tall blocks whether single or stacked act like a breaker bar on the springs and u-bolts. It can cause wheel hop and vibration as the axle can move front to rear twisting the springs and u-bolts.U-bolts can stretch causing the blocks to pop out. 2-3 inch blocks are normal, staying 4 inch and under is recommended. I'm in the never ever stack blocks camp. It's stupid and dangerous.