I have none and I guess I need both the shifter slider from Classic (or Firebird Central) and a rubber seal kit form Smmit or Rick's?

Rick's description add this: Steel Inserts As Original.

Anyone have any experience here?

Don't buy Pontiac parts from anywhere but Ames Performance

Another mystery?

Ames and Classic Ind have the shift lever/plate slider seal (these are plastic). Neither carry the 4 rubber seals. The IPC shows the slider seal #9 and 2 other seals #s 15 and 16.
http://www.tpocr.com/68-69fbconsoleipc.html

Does anyone with a 68-69 with AT have the 4 rubber seals on their shift plate or is it just for Camaro?

Those rubber pieces don't look like the two rubber pieces that are shown in the link you posted #15,16. My guess would be , the 4 rubber pieces are for the Camaro Horseshoe style shifter. I have not seen them pieces on my 69 shifter, unless the 68's are different.

Also, not sure when they came out with the style of shifter that you can push to the side as you up shift to only go up one gear at a time, my 69 shifter is like that. It takes a different slide seal, it has an oval hole in the middle to allow the shifter to move to the side. Just in case your shifter is like that.

The ratchet shifter came out in 69. I had one in my 69 goat

Installed the Console Shift Slider from Classic Ind. (Seal, shift lever) last night. Seems weird how it fits under the bracket, but works just fine. Also, Firebird calls for gray and Camaro for black, but it looks like the black would look better. Oh well, I have a tight shift plate now!

Are you missing the housing assembly and light for the gear indicator? The lens looks transparent in your photo.

No, it's all there and the light works. I think it's a bad reflection.

But, it did prompt me to clean up the lens, paint the backing, and re-align when I re-install.

Very good! My shifter plate has been loose on mine for decades. The clips just won't hold it tightly and I know of no way to fix them. For 30-40 years I've had some folded cardboard jammed under the front edge of the plate to hold it firm yet it's not visible. Some day I may trip over a solution.

If it's the clips, not sure what you could do...

But on mine, the previous owner had washers (spacers) under the bracket on the the 3 bolts that hold it down. With the bracket at the right height the plates fits nice and snug.