A500 or A518?

I have two of these trans and researching this as I type.
One from a 92 v6 dakota and one from a 96 v6 dakota
I am just trying to figure out the differences between the 42re and the 42rh. Guess I should put them side by side.

I was going to scrap them but I had a nightmare about overdrive and a big block.
I already planned the big block to slide into the dakota plus the 727 trans.
If I am going to rebuild the trans anyways overdrive would be nice since i already have it