OOC: "What's Yours Is Mine"
So, at least according to reading through the episode transcripts, here's what all is canonically stated as parts of Grif that were replaced with parts of Simmons:
- left hand
- "we had to start at the shoulder, then we moved on down to the flank, made a left turn at the spare rib, up and over the porterhouse. And, of course, the brisket, and the hocks. Ohhhh, the hocks." (Lacking an anatomy book, Sarge used a dashed-line meats-cut diagram of a cow.)
- Testicles (Simmons: "Yeah, I'm real happy about this myself, numbnuts." Sarge: "Yep, those too.")
- ass
- "We pretty much replaced all the internal organs, and some of the more disgusting external ones. Except for Simmons' spleen, which will be inflated and used for general recreation, and esprit de corps."
- sweat glands (which don't work right)
- lungs
- cerebral cortex
- negative emotion center
It's possible that more might've been revealed, except that they pretty much stopped with that line of jokes -- and Simmons 2.0 references, for that matter -- not long into Season 3. Also, I notice that at one point, Sarge outright addresses Grif as "Frankenstein". Hah.