I am just testing the waters here, guys.

  I am restoring my grandfather's old '49 CJ3A. I am wanting to add turn signals, but don't want to add front turn signal lights or have to modify existing front parking lights.  I have spent months on forums and blogs, reading post after post, reviewing mods and diagrams, etc. I finally got my hands on several different vintage turn signal switches and tore them down to do some research.  First off, I am an industrial controls electrician, so I was able to delve into the functionality of the inner components without much trouble.  Interestingly enough, I was able to find one model that allows me to do exactly what I wanted.  I also found that I can modify other models to do the same thing.  I now have switches that allow the front factory single-filament parking lights to function as both parking and turn signal lights.  All that is required is running a separate wire to each front light (basically, just running one extra wire), and a separate wire to the brake lead of each taillight.  Or just purchasing a wiring harness equipped with turn signal leads.
My question here is, would anybody be interested in buying these switches if I started doing the modifications, installing new wire leads, and basically refurbishing the units to sell as a complete kit....including a flasher relay and mounting hardware?  I know I would have definitely jumped at the chance to buy one several months ago, when I first started this journey.
  I was thinking that if there is enough interest, I might set up a little side business putting these kits together and selling them for about $100 to $150, depending on finish (some would be chrome body, when available, others just repainted), and overall condition of units.  I have even come across a few NOS switches.  A wiring diagram and basic instructions would be included as well. I would be able to offer them in 6 or 12 volt versions. Sorry, these units are not the "self-cancelling" type. 
  So you guys let me know if any of you would be interested, and I might start taking orders.  Otherwise, well,  guess I'll sell the extras I have on eBay, and forget the whole idea....

Hey JonL,
I did this same thing last summer. I wanted to add turn signal capability to my Jeep but keep my original single filament front lamps.  I found that the older 800 series Signal Stats did have allow turn signal and parking lamp functionality with single filament lamps, but they're long out of production. So that leaves us with the 900 series Signal Stats, but they require dual filament lamps.
Soooooo....
I took my 900 apart and noticed that the buss bars inside the unit could be modified to allow exactly what we want: the ability to pass parking lamp power to the single filament front lamps, or inject the turn signal power. It's essentially the same thing the REAR tail lamp/parking lamp does...single filament used for both parking and turn signalling. The mods I performed involved cutting a bar, creating some new contacts with some brass screws(the sockets are empty in there ready to use!) and some soldering inside the unit. The mods are highlighted on my "1950 CJ3A nuthin' fancy" thread, post #86. in the "Your Stock 3A Project" section of this forum.
http://www.cj3apage.com/cgi-bin/3Ayabb26/YaBB.pl?num=1414467408/75#75
For me, the mods were simple, and worked perfectly, but I can see where alot of folks wouldn't want to do this...lots of small detail work...I'm thinking there may be a market. You could probably also sell a bunch at one time to some of the Jeep suppliers, although they'll definitely want 'em at low cost! Good luck!

Tom,
  I'm away from my shop for a few days, but I'll try to get some picture up when I can.  Thanks for the interest.  -Jon

First pic is before modifications.  Second pic is switch opened before mods.

This pic is of new contacts rivets and washers installed, and next pic is of contact side of same board.

Pic of new wire leads soldered in place, and board installed back in switch housing.

Wiring is pretty simple.  one lead takes place of parking light wire on headlight switch.  One wire replaces brake light wire on brake switch at master cylinder.  One wire each to front parking lights and rear brake light leads. (if you don't already have one, you will need to install a second brake light on rear passenger side). The last wire is the one off the flasher with the inline fuse.  it connects to your ammeter on the instrument side. (opposite the lead coming from your voltage regulator or alternator).

If you call and I don't answer, just leave a message.  I work in a paper mill, and often don't have my cell phone with me.  I'll get back  to you as soon as possible.  Thanks!  -Jon L.