Does anyone know if they made a cover for the Fender Rhodes amplifier speaker (80 watt Peterson)
Yes, Fender offered vinyl covers and hard cases for the suitcase Rhodes.
Here's a link to the price list thread which includes prices for the covers: https://ep-forum.com/smf/index.php?topic=5694.0
I've seen a few of the the Stage vinyl covers before and I think I've seen the hard case once, but I've never seen the speaker cover. It probably wasn't a common accessory and with the suitcases already being a lot less common than the stages, I doubt many were made. Add in the fact that most owners could barely hang on to their case top, 4 pin cable and braces/pedal/legs/vinyl leg bag (for stage owners), I couldn't imagine many surviving till today.