To answer your question, although the 80 locks are very similar you won't be able to put the lexus/jdm sidewinder wafers fully into an fj80 lock. This is because the last 3 wafers on the lx450 lock are dual/split or "half size".
I will share what i learned about the lx450/hdj81 door locks due a recent attempted break in to my passenger door on my JDM hdj81. Both hdj81 and lx450 use the sidewinder sidecut and also the same door locks. If your door lock is damaged, your only dealer option is a full lock cylinder set at 350$
690056A260 Toyota CYLINDER SET, LOCK Price: 354.47$, Weight: 0.773kg - PartSouq - Auto Parts Around the World.
I could not stomach paying out that much for a busted door lock, but also had hard time finding a used lx450/hdj81 door lock. i ended up visiting my local pull-a-part yard and got a lock from a 90-96 lexus ls400 for 5$ (bring a 10mm socket on swivel/Ujoint or you will end up having to cut away part of the sheet metal on the door to get the socket on). You could also likely get the same part from similar age es250/300, gs300 or sc300/400. The ls400 part is exactly the same with the addition of some extra wires/position sensor that clips onto the lock, and once removed is the exact same part as the lx450/hdj81 lock (even had the same numbering).
You will still need to rekey the new lock to your old key. A locksmith can do this using a lexus TOY40 wafer/tumbler kit either using your old key or the 5 digit key code (If you don't have this it is stamped on the RH door lock). The lock smith will use software to obtain the wafer numbering for your 5 digit key code or manually using the old key/lock if necessary. Not sure how much this costs, but others have paint several hundred dollars to have this done.
Or you can if you have the required wafers you can disassemble the lock yourself and rearrange/replace wafers as needed.
For a good tutorial see this thread (uses fj80 lock, but still applicable)
Servicing a door lock cylinder
If you go this route, i suggest grabbing some extra locks (preferably from multiple vehicles) from the pick-a-part, that way you have a good chance of getting all of the needed wafers (pins or tumblers). There are only 5 sizes of wafers in two flavors (full and split), so there is a good chance that the replacement locks will have all the wafers needed. In my case, half of my lock was literally gone, so i was only able to salvage a couple of wafers from the old lock, but by rearranging the wafers in the new lock i had all but 2 of the needed wafers which i removed from a 2nd lock.
Regarding copies of keys, the blanks can be had very cheap by ordering an ilco lxp90-p (5-10$ ea), but i found it hard to find someone willing to either copy the old key or cut a new one from the code. The locksmith wanted 25$ to cut a blank i provided. Lexus dealers varied from 50-200$ cut they key from the code (including the cost of the oem lexus key blank).
Below is a re-posting a DIY on i found useful from the toyota nation blog as well. I will note that, contrary to what many others suggest, they advise against using graphite power on toyota locks. After rebuilding one i would note that the pins are clearly lubed during assembly with a waterproof grease. After dumping graphite in my ignition for preventive maintenance i am hoping it does not gum it up in the end. So far it is ok...
https://www.toyotanation.com/forum/...rebuilding-rekeying-toyota-lock-cylinder.html
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Rebuilding / rekeying a Toyota lock cylinder
First note the construction of the lock cylinder. Through the drain
opening on the bottom of the cylinder you can see the spring-loaded lock
wafers. They follow the cuts of the key, and are all flush when the
correct key is inserted. The closed end of the cylinder has a c-clip
holding on the activating lever and the return spring.
Now on to dis-assembly.
Pry off the lock bezel.
The stainless steel cover is staked into place at two places on the
outer ring. You need to partially pry out one of the crimped spots, but
you don't need to bend it back much before you can pop the lock bezel
off.
Insert a key. Even an uncut key will work. This will keep the wafers
and springs from popping out after the next step.
Remove the C-clip on the rear of the lock cylinder. Remove the
activating lever and return spring.
Push the interior assembly from the external cylinder. Push from the
c-clip end, don't pull the key.
Note that the lock cylinder has eight wafer slots. Two of the slots
have split wafers to make the lock more difficult to pick. Each wafer
is lifted by a small spring underneath. If you have the correct key the
wafers will be flush with the surface, otherwise the wafer will project
from one side or the other.
Put the interior assembly into a plastic bag or enclosed area. Pull the
key out. If the lock is still well lubricated the wafers will pop out,
freeing the tiny springs to find dark corners. If the lubricant has
dried out the wafers will remain stuck into place. If you need the key
code, pull the key out incrementally saving each wafer in order.
Each wafer has a key cut depth code from 1 to 4 (or 5 for a lexus key) stamped on it. If you
saved the wafers in order you can read these, starting from the key
shoulder, to get the key code. If you mixed them up, or are rekeying a
used lock to match your key, you can go slot by slot, trying each
wafer size to see which sits flush with the key inserted. With a little
experience you can just look at the key and read off the depth codes.
If you are rekeying an old lock cylinder don't worry if you run short of
a wafer size to fit your key. Not all of the wafer slots need to be
filled. Missing wafers will make the lock a little easier to pick, but
have you ever heard of a car thief using a lock pick?
Reassembly is almost as easy as taking the cylinder apart. Clean the
old lube off of the parts with solvent. Find an appropriate grease --
clean, stable, wide-temperature range waterproof grease. I use white
lithium grease. Fill the upper slot in the outer cylinder with grease.
Force some grease into each wafer slot, taking care to get enough into
the spring end to keep the spring from falling out.
Now we have to load the wafers into their slots. You can incrementally
insert a key while you load springs and wafers into their slots. Or, if
you want to live dangerously, load all of the springs and wafers on one
side, and hold them in place with a finger as you flip it over and load
the other side..
Now reassemble the lock cylinder. Turn the key until it mates
completely. Load the spring into its position, which will require
putting a little tension on it. Install the activating lever so that
it's projection is between the two spring ends, and snap on the c-clip.
If you filled the cylinder upper slot with grease, enough should have
squeezed out to lubricate all parts of the lock. If it looks a little
under-lubricated, smear some into the lower slot and around the spring.
The lower slot can't be packed full of grease or water won't be able to
drain. Insert key a few times, wiping it off each time, to squeeze out
any grease from the slot.
One point of confusion is the lock lubrication. Brass locks are
sometimes lubricated with graphite, but car locks usually use waterproof
grease. Putting graphite into the lock is a bad idea. The wafers are
such a close fit that pretty much you can't re-lube the lock from key
hole.
