I've checked ebay, there appears to be one but it looks questionable (photos are realy bad and I can't tell if it's correct). If anyone has one they would part with or ideas about alternatives, I'd love to hear about it!
You might check the link below out with the vendor and ask about measuring the bottom plate, whatever that is called. I have a PM 45 and an old Oliver which has a banjo that will fit the 45, except the tool rest hole is smaller.
Also, I don't know why any brand with a 2 1/2" gap wouldn't work, and even then just changing that bottom plate with different gaps might make other brands be an option as long as they are for 6" height above the bed. However, you'd be lucky to beat this $50 price.