Those are Kohler numbers.
I was able to Goggle the tank lid number.
How old a toilet is this?
Just yanked an older toilet, with the following markings:
A large blue K between the seat and tank
inside the tank a K4524 above a 70973 and a red stamp F-25 (inspector?)
under tank lid K4552 above 7973 and a large 3.
Anybody have the decoder ring?
Not really sure, original homeowner lived here for 40 years, however, the toilet is elongated (not sure how far back those date) and it had a plastic nozzle on the wax ring (not sure how far back those date either). Also had the fluidmaster 400A fill valve and it had a flush valve seat repair. House was built in 1960. Found about 1/8" of hard water deposits in the trapway which was probably the reason it flushed poorly.
The 1/8" may not have made a difference, but a similar amount in the part between the tank and the bowl probably would - it would have slowed the amount of water dumping and the bowl wash. My unprofessional opinion! There's a big difference in the quality of flush on new toilets, and there are old ones, even with a huge water flow, were junk, too.
Important note - I'm not a pro
Retired Defense Industry Engineer
The ceramic date is molded into the china like the kohler number.