Are all of the threaded holes on the cats supposed to have studs or are some of them supposed to get bolts from the top? I think just the bottom one on both cats is supposed to be a stud right? Thanks guys getting ready to put back to stock for smog check and had to buy new cats as mine were rusted badly and the ones I bought only have one stud out of 4 threaded holes ( cat side)

 

Yes. Just bolt up the connections

 

I've got 2 laying around if you need another!