I've always used a prybar as a holdback.

 

BINGO, make sure they are holding the stand

 

2j not an ls motor but same concept:

 

Tyler (dirt_track_racer_81 did it on my motor a few years back

 

 

bingo. thanks guys. this trick has always worked great for me. i'm always working alone so the screwdriver in the flex plate is a pita and i never have someone around to hold the back of the engine. the belt trick is easy and works when i dont have 2 extra hands.

 

It worked great for me too. Dirt track racer was the first to post this concept several years ago

 

I usually shove a breaker bar in the side of the crank pulley and wedge it against the frame...

 

that works great for removal, but not so good for putting it back on if i remember correctly. also, aftermarket underdrive pullies are solid so you can't stuff a breaker bar through it. 3rd if the motor is on a stand, there is no frame below to wedge into. and finally this would be on an s10 application so i dont know what the frame looks like down there...there may not be anything to wedge on a LS swapped s10.

 

I used a vice grip tightened down really good on the flex plate and an impact.