Is it common for a loose flex plate bolts to sound like a rod or bad piston 4.0 1999 WJ?

Similarly, a cracked flywheel will offer some "great noises" like a rod, ect. Would surely check the bolts first. GL!

Well I checked torque converter bolts for loosemess and they were fine no sighns of cracked flex plate what so ever I'm gonna pop off the valve cover as I had it running and drove it up on ramps the knocking noise even under a load could hardley hear it and the longer I had it running the quitter it got that doesn't sound like a rod or main or piston !! sounds more like a calapsed lifter hangin up on number 6 cylinder as when it was the noisiest it seemed to have a miss or stumble in of valve not opening or closing .. The rest of my jeep is in such good shape no rust dents a few very small scratches suspension tires ,differentials you name it I replaced everything in the last 2 years and used it for something to do rather then sit and watch tv eatin pizza,s as I haveother vehicles for work and such so I think next weekend I,m gonna pull the motor and take it to the machine shop . Thank you all for the help and responses and I,ll let ya all know what the mystery knock ended up being!! So I'm gonna Keep on wrenchin