j bolts with mopar style perches?

[turbo69bird]

The stock eliminator guys often run mopar style spring perches. Can you run j bolts with those perches? Would you even want to? Vs U bolts

[turbo69bird]

I think I have my answer based on a picture I found with U bolts and J bolts next to them. J bolts I guess just for pre load. This is on a ford .