I recently moded my FT-897 with an LDG Z-100 autotuner that fits inside of the battery compartment.  You can see a couple pictures that I uploaded in the photos section under the K4SGT album.  Here is how it is done...


Obtain an FT-897 transceiver.
Obtain an LDG Z-100 autotuner.

Open the Z-100's plastic case and remove the circuit board.  From here you need to decide if you want to keep the back panel of the Z-100 intact or if you want to hard wire everything in direct.  I opted to keep the panel (since it is marked with what port is what).  You will need to reduce the size of the metal back panel in order for it to fit into you 897's battery compartment.  I cut it down with a dremil tool until I was satisfied.  This whole board will mount to the metal plate that seperates the battery compartment from the xmitter board.  I placed a thin piece of fiberglass between the Z-100 board and this metal plate to keep any componets of the Z-100 from grounding out.  Before you mount the board you will need to remove the two LED's and the push button from the front of the Z-100.  You should keep track of just exactly what went where so that you can reattach these parts.  Well, the parts don't reattach directly.  You will be remoting them to the top of the radio.  In my pic you can see the bulk of wires going into a hole to the other side of the radio.  You need to run a wire for every lead that you remoting (10 wires...if I remember correctly).  I braided mine with it's mate so that it was less confising.  Drill a hole on the top cover of your 897 for each of your LED's (I did this just above the battery selector switch...as you can see in my other photo).  Oh, and that battery selector switch acts exactly as the push button switch on the Z-100 so you can make it your new autotuner switch.  Get out your continuity tester to figure out how exactly to wire it just like the old push button was wired.  Now you need to power the Z-100.  You can remove the metal cover that is keeping you out if the xmitter board and find power there.  I am drawing power from a couple of spots located directly next to where the main power comes into the radio.  It really looks like these two holes were just waiting for me :).  If you can't find what I am talking about then grab you voltmeter and find the 12+ volts that you are after.  If you still can't find power then you probably forgot to plug your radio into a power source.  If you still can't find power then remove your Z-100 and close the 897 before you ruin everything.  Okay, back to what to do.  So we have power, LED's, and an activation switch...we need to attach the HF/50Mhz port.  You can gain access to the back side of the SO-239 chassis mount port by going back to the xmitter board.  Here you want to desolder the connector from the board and solder on two pieces of coax (one from your board and one from your connector).  Both of these cables will run to the Z-100.  Mind the in and out ports on the Z-100 and attach the appropriate line.  Here if you kept the Z-100's metal panel you will attach a PL-259.  If you chunked the panel you simply need to attach the coax directly to the Z-100's board.  The last thing that you need to attach is the autotuning cable.  Don't waste your $12 on buying this cable.  It is nothing more than a straight through stereo 1/8th inch cable (headphones style).  You don't even need both ends if you decide to backdoor the connector like I did.  What I mean is instead of running this cable out the back of the radio and plugging it in (which you can if you want to) I went through the same port that all of the other Z-100 wires are remoted through.  You can then directly solder your wire to the board where the port is.  This will still enable the use of the port on the back of the radio.  All in all, when it is done, you will have a 100% internal and quite nice autotuner.  To operate it you will simply throw the switch on the top of the radio.  The red LED will light (keep it on for 6 seconds for full tuning cycle or 2 secondsfor memory tuning).  Throw the switch back for a quick second and then back again.  The tuner will tune.  When it is finished if successful the green LED will either light solid green of flash green.  If you did not get a good tune then only the red LED will flash.  After the tune is finished you should throw the switch one last time back to the off position.  The tuner is good for 125 watts on all HF bands and 50 watts on 6M (be sure to reduce your power on 6M or you could damage your Z-100).  You can bypass the tuner by throwning the switch on and off once quickly.  The green LED will flash letting you know it was just bypassed.  This way you can still use the radio without your tuner.  To re-enable the tuner simply go through the tuning process once again.  This mod may not be for you.  If you like the Z-100 and you would like to have an internal tuner and you are tech savy and you are skilled with a soldering iron...then game on.  -Note- The steps given above are in no logical order.  You are probably better off starting with the rf cabling.  I'll leave the order of what to do up to you.  Remember, you are responsible for your actions.  If this mod is over your head then don't try it.  Good luck!  Barry K4SGT