How possible is it to transplant hard disk platters, at least for the purposes of data recovery when a drive mechanism is otherwise physically dead?

In particular I have a 40MB 2.5" SCSI Conner HD and an old style IWM Hard Disk 20. I would imagine if it i possible, I would need working drive mechanisms to sacrifice. Once cracking the drives open, I would assume that I have basically destroyed their reliable useful life?