You need 6V bulbs.  That bulb was a 6V bayonet.  You can go with 6V GOW and tape to shell to get effect, or go with LED with limiting resistor.  G

Many Thanks that's what I needed to know. Found source for bulb. As far as the 2nd question of adding a rear light. Can the lights be daisy chained or is there an output source on the board?

The 12 pin connector slot next to the blue wire is the slot for reverse.  Pin 4.   Pin 2 is the purple wire or looks like red in this case that is Positive voltage and would go to the bulb too.  You need to add the extra wire in slot 4 to get reverse control for the bulb.  G

You can upgrade those bulbs to LED's for nicer looking headlights.  If you have the correct sound file, you can also get independent control of the cab lights, and even add marker lights if you desire.

Thanks gents. John, was wondering the same. I've upgraded a number of 3 volt boards and have the schematics. But was unsure of the 5v board if the pin locations, power sources, and harnesses were the same. Let me know if they are, and I can figure it out from here. If not does anyone have a schematic. As far as the LED, George indicated a resister would be needed. Is there specific specs for the resistor. Sorry to bother you folks and keep this thread alive. Good info for the future.  

Pinouts are the same on the 3V and 5V boards.  I use a 220 ohm resistor with the white LED's for headlights.  The marker outputs are actually designed to drive LED's directly, usually two red or green one in series.

Here is an older post that may help with the LED lighting.

Forum List / Control System Forums / MTH DCS and PS2/PS3 / LED Headlight replacement for ... LED Headlight replacement for MTH locomotives. Post New Topic      Marty Fitzhenry  OGR Forum Member   April 18, 2015 6:43 PM     Over the past years I have done many DCS upgrades.  Several people wanted bright white LEDs in headlights and backup lights.  My good friend Locolawyer is the guy I blame the most for this request.  Recently I have had members ask me to throw something on the forum instructing how it is done.  Very simple and very cheap to do.  On PS2 and PS32 boards the wires for the front headlight are light blue and purple.  Light blue coming from the number 5 pin on the 12 pin connector and the purple comes from the 2 pin on the 12 pin connector.  The rear lighting is a light green wire from pin 4 on the 12 pin connector and the purple from pin 2 on the 12 pin connector.  On front and back lighting, follow the purple wire to where your lights plug in.  The purple  is the hot wire and the corresponding wire that you need to put your resistor in on the light side of the plug.  Cut the wire and insert a 560 OHM 1/2 or 1/4 watt resistor.  Next cut the bulb off the wires and connect the longest lead from the LED to the other end of the resistor.  The long lead is plus.  Connect the other wire (negative) to the ground side and you now have LED headlight/backup lights.  I will outline this a bit better with a few pictures.     The photo above shows left to right a section of 3/64 heat shrink, a section of 3/32 heat shrink, next a 3mm bright white LED.  This is Lionel p/n 6102045300, and a 560 OHM 1/2 watt resistor.       Above is the resistor I used.  You can buy what you need at many locations and they are very inexpensive.  No polarity is needed.         Above is a front MTH conversion showing the light blue and purple wires used in the front headlight.  This is the original incandescent light from the upgrade kit.       This shows the finished product without the shrink to show you the path of the purple wire to the resistor then to the LED.             This photo shows the final product with heat shrink installed.         This shows before and after.  You are out about 20 minutes of your time and about two bucks.  If you like the LED look, anyone can do it with no special skills.  The LED I used was from Lionel and the resistor from a local parts store.  You can use any manufacturer of the products.  I did some testing with these a long time ago with MTH R&D and the correct resistor we came up with was a 510 OHM.  You can go down to that if they are available to you.       This is an MTH PS1 upgraded Hudson for Locolawyer.       The rear of the Locolawyer Hudson.   Marty Fitzhenry   TCA-79-13758 TTOS-3057 LCCA-28444 LOTS-RM-4833 MTH DCS and Wi-Fi Beta Tester MTH Factory  Certified Technician-5 schools Lionel Factory Trained repair Technician #10140 Member Mid America 3 Railers and NJ HiRailers

Marty, how did you come up with 510 ohms for the resistor?  I use a 220 ohm 1/4w resistor.  If you use 6V as your operating voltage, the 220 ohm resistor only dissipates .05 watts and the average current to the LED is around 13 ma. 

John, that was worked out with Jason at MTH.  Many years ago.  Has worked perfect with not one issue.   

Marty, I'm sure it'll work fine, I just like to run them a little closer to maximum brightness.  Just curious where the values came from.

John, I hear you.  This is bright as the sun and hopefully will outlive all of us.   I tried to have Mike do this as a product for sale.  To make one at the rate he buys parts  for should cost about nine cents to make.   What do you think people would pay for one all made up?  Guys like Evans do some fantastic LED set ups.  This would be for a direct swap into MTH products.

You could probably make up the light connector with an LED and the resistor, the parts can't cost more than around a quarter, the connectors being the most expensive.  The LED is five cents or less, and the resistors in quantity are about a penny.

John, Marty, and George - great detailed "How To" reference information. I'm sure many others will also benefit from this post.

Many Thanks