Those heating elements are embedded into the foam bun, when the stuff is molded. Only way to replace the element is to replace the foam. Good luck on finding that! If you ever do, let me know. Been looking for a pair of those for a long time. GM discontinued them years ago.
My buckets came out of a '97 Escalade. The heater control next to the positioning controls on the seat.
My black truck came with a bench. When I hooked up the stereo, I ran a 4ga wire off of the battery to under the passenger seat, into a distribution block that has four spots to hook the amps into. I only used two. So, I used the other two for the power to the seats. I grounded the seats to the front inside floor bolts, then ran every wire that is for power to dist. block. Since the heaters don't work in mine, there is no constant draw for power. Only an occasional draw when adjusting the seats. Not enough to worry about burning anything up. And the 4ga. is fused anyhow. It's been wired like this for 7 years. Never had a prob.