IIRC, originally the top assembly was four pieces. Two behind the fence ¾" x 1½", and 3" x 40". Then you had a fence 1½" and a front piece 16", both x 40". The reason for the two different sizes for the rear was to be able to switch them to accommodate different thicknesses of stock.
You can make table pieces very easy. Set a piece of ¾" anything (plywood, particle board, or MDF) On top of the table frame near the blade. Push the saw all the way back. Take another piece of whatever you think you'll be using most...(example:...you could allow as much as 6/4), Place it in front of the blade but don't allow it to touch the blade. The backside of that piece would be where the front of the fence should be placed.
From there, you can figure out the size of the back piece that gets held in place with the turn screws. This gives the longest cut according to the thickness of the stock being cut. If you need to cut stock thicker than 6/4, place spacers behind the stock against the fence.
I prefer to machine a small rabbet where the fence meets the table, as a pocket for sawdust. IMO, it's easier to blow it out of that little groove than picking it out of a tight corner. It also allows stock to fit to the fence while cutting. If the table is all one piece, the whole section has to be replaced when necessary instead of just the front section.
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