Thank you for your reply. He was 20 when I filed and now he is 22, but still qualifies as a child under IR-2.
We did file all our taxes as MFJ, so am happy to provide all three years' transcripts. But on the I-864A form, the instructions ask for 1040 along with ALL W2as well. It doesnt make sense to me to submit our 3 years' transcripts from the IRS, PLUS the 1040s and all the W2s. Also, from what I understood, if my income alone is sufficient to sponsor him, why does my wife need to submit an I-864A? I earn close to $53K and she earns over $55K. Together, we make around $110K a year, and for my son's immigration, we only need around $325K income. So it is a bit confusing.