All 500-series projectors can use the 581 tray.
All 500-series Argus projectors can use the 587 tray. It holds 87 slides.
Vintage slide projectors can most likely be found at a local Pawn Shop. If one cannot find a Vintage slide projector as their local Pawn Shop, good places would be to look on Ebay, or Craigslist. People can be offering these projectors.
20 Jones Street New Rochelle, NY
Reel to Reel, Overhead Projection Slides, and Carousel Slide Projectors.
Yes, RadioShack does carry the top brand name HD projectors. They have a great selection of projectors available at reasonable prices.
Yes, LCD projectors come with a variety of inputs. Depending on the age or manufacturer's intended use, you'll be able to find LCD projectors available with inputs ranging from VGA and coaxial all the way to Component, DVI and HDMI.
Sadly, slide projectors have had their day and it is virtually impossible to buy a new slide projector now. The best idea is to look at online auction sites. There is a steady stream of used projectors for sale and it won't take long to find either a B&H or a compatible model.
One may go to youtube to find informational videos about 16mm projectors. 16mm projectors are also available for purchase on such sites as Ebay and Etsy.
Slide projectors are considered "old technology", but if you have slides and a projector, showing them would emphasize that you and your dad predate PowerPoint. And that's not a bad thing.
All 500-series projectors can take the 593 tray.
LCD projectors are used to project video or images onto a flat screen. The technology has almost replaced the older slide projectors or over head projectors. The picture is much clearer than on old technology. A common use of LCD projectors is to project song lyrics onto a screen during church services or to display powerpoint slides during a college lecture.