Product review (5 stars): 12001596 is a virtual replacement for 8053421
I chose the title for this review because the uncertainty of the part number equivalencies almost kept me from buying this.  I say "virtual" replacement because, like the other reviewers, I had to replace spade connectors on four wires to get them to plug into the new part.  But to save around $80 compared to the higher priced 8053421, it was well worth it.  The four ignitor terminals on this part are narrower than those on the original spark module, hence the need to rework the connectors. Tools required: wire strippers, long nose pliers, and if you're a purist like me, about 3" of 5/32" shrink tubing to insulate the finished connectors.

The four replacement spade connectors came with it. There was also a metal mounting plate which I didn't see the need for because, unlike the pictured module which has descending clips on both ends, mine had a slotted tab on one end which mirrored the style of the original part.

It all came in a bag marked "Whirlpool Factory Certified Parts", so I still don't see the reason for the big price difference on the two parts.

Operation: the new one sparks more rapidly, about 8 times / sec vs. around half that frequency for the old one.  Works like a champ!