I found a prop/combination valve in my stash with the broadcast code "LF". I couldn't find that code in the parts catalog. Can anyone shed a light on what cars/brakes they were used? I absolutely don't remember from what parts car I got it...

Late PBR. It's not in the book, but it's the 91ish 4 wheel disc valve with or without the dual piston aluminum front calipers.

Interesting! Thank you! So I will be able to use it in my 92 with rear PBR calipers and LS1 front brakes?