Magnum flex plate 904 vs 727: identification?

Any LA flexplate will work. Even a junkyard one that's not cracked. They can be had for $5 or so. Opening up a hole in a part that requires the engine and trans to be separated to change out is just a good way to be really pissed off when that plate cracks and you have to waste a whole day changing it.

If you're spending the time and money on a crate engine, why not just do it right?