I managed to integrate the freeware TCAS II gauge from flightsim.com (search: TCAS II gauge)

Remember to back up your 727 panel.cfg before changing anything.

Follow the steps in the TCAS II folder for installation.

Here is the section from the panel.cfg - just copy over the sections changed here in the panel config.

[Window02]
size_mm=349,845
position=8
background_color=25,0,0
visible=0
windowsize_ratio=0.75
ident=RADIO_STACK_PANEL
gauge00=Captain_Sim.p721.P10!P10_001_vhf,  0,  0,349,190
gauge01=Captain_Sim.p721.P11!P11_001_vhf,  0,190,349,190
gauge02=ILH_TCAS!Transponder, 0,380,349,155
gauge03=Captain_Sim.p721.P01!P01_001_adf,  0,535,349,155
gauge04=Captain_Sim.p721.P07!P07_001_adf,  0,690,349,155

And in [VCockpit01] replace line 07 with:

gauge07=ILH_TCAS!IVSI, 16,520, 219, 222
//gauge07=Captain_Sim.p721.L11!L11_vsi, 20,524, 217,220

and add this to the end of [VCockpit01] you know what to do with xx

gaugexx=ILH_TCAS!Logic, 0, 0, 1, 1, trafficinfo:yes volume:-100

If you use FSUIPC there is no need for the last part: trafficinfo:yes

Also for the F/O side [VCockpit07]

EDIT

gauge05=ILH_TCAS!IVSI, 12, 516, 219, 222
//gauge05=Captain_Sim.p721.R11!R11_vsi, 20,524, 217,220

http://i1117.photobucket.com/albums/k586/CNmodeler/TCASII_zps0acc64be.png

Thanks too Lee Hetherington for his TCAS gauge.

Enjoy!  ;)

Very nice! may have to try this as i fly the 727 almost exclusively for FedexVAC, seeing the new transponder made me think for those that want an updated VC (or for me the start of one) how impossible would it be to change the tone of that transponder to boeing gray then replace the radios with the new digital ones from say the 767 or T7 and change those to the Boeing Gray panel? Just so the tan doesnt look out of place. ::) :-?

I will give it a shot! Could be easier to use the default 737-800 radio panel and just change the transponder panel to grey. I do know the gauge is useable with squakbox3, so it should work with vatsim

EDIT

I can't seem to find the texture file for the transponder, it's going to be beige for now...

So heres another idea ill throw at you, what IF we used the gauge ( IF it is one) of the TCAS unit from the CS737 along with the Transponder from said plane, Possible? No? any one else wanna weight in

Hello, I'm really interested in having this improvement, the TCAS, but when I look at FlightSim not find it, could you give me a download link ?, or you Might send by email the folder with the gauge? my email is cesarleyton77@hotmail.com, really I am very interested in being able to have, thanks.

File το DOWNLOAD and install is ilhtcas4.zip found in popular file libraries.
Documents included should be read for installation.

My changes to -200 model panel.cfg for CS727 ver2.6

[Window04]

//gauge02=..\..\CS_B727-100\panel\Captain_Sim.p721.P13!P13_001_tcas, 0,266,184,109
gauge02=ILH_TCAS!Transponder, 0,380,349,155


[VCockpit01]

//gauge07=..\..\CS_B727-100\panel\Captain_Sim.p721.L11!L11_vsi, 20,524, 217,220
gauge07=ILH_TCAS!IVSI, 16,520, 219, 222

(last one, number 41 due to CIVA INS setup)
gauge41=ILH_TCAS!Logic, 0, 0, 1, 1, trafficinfo:yes volume:-100


[VCockpit07]

//gauge05=..\..\CS_B727-100\panel\Captain_Sim.p721.R11!R11_vsi, 20,524, 217,220
gauge05=ILH_TCAS!IVSI, 12, 516, 219, 222

Screenshots of how it looks:
http://hellasga.com/gallery/kyp/fs/fsx/cs727/tcas_wx
http://hellasga.com/gallery/kyp/fs/fsx/cs727/tcas2

It was more than 10 years ago when I did the same for the DF727  :)
http://www.flightsim.com/vbfs/showthread.php?150838-DF727-panel-ILH-TCAS-and-Transponder-for-on-line-flights

One small correction on the above, the file to download

ilh_tcas_v4.zip

Until P3D 3.1 Lee Hetherington's TCAS II v7 IVSI and Transponder gauge was compatible with P3D.

Something changed in 3.2 and the transponder appears just as a brown background rectangle without any functions.
The IVSI works but in Squawk Standby mode.

To enable again this wonderful gauge in P3D past version 3.2 do the following:

Create a folder ***OUTSIDE*** P3D folder for older add ons like E:\AddOns and inside it a subfolder Gauges

Find gauges.cfg in C:\ProgramData\Lockheed Martin\Prepar3D v3

Make a back up of the file somewhere and change it with notepad as follows with the new Entry.1 as follows and save it

[Entry.0]
Title=Default Gauges
Path=Gauges
Required=True
Active=True

[Entry.1]
Title=Addon Gauges
Path=E:\AddOns\Gauges
Required=True
Active=True

Next time you load P3D the Transponder will be visible in your aircraft.

http://i.imgur.com/SYvmJn1.jpg