The TRS 80 Model III with Texas Peripherals 10-5355 drives. The top drive in this unit (drive 1) is not functional so I replaced it.
After testing thoroughly, I determined that the index sensor was bad, I could not verify a formatted disk. I decided to put in a new drive rather than fix it. First I put in an IBM Tandon 100 2A, it worked but it looked funny with the "IBM" logo. I settled instead for a TEC FB-2002-TR000 drive. The two drives look different, but they work.