Pertronix ignitor, which one to use

Maybe some out there could help me. I have a 1961 TR3A, the numbers on the side of the dist. reads 955v167 40403D DM2.
I converted the system to negative ground. I ordered a Pertronix ignitor for this dist.. The part number is LU-149, but the ignitor does not fit. I have another 61 TR3 and this ignitor fit that dist. with no problem. The mounting plate doesn't fit due to the vacuum advance post is in the way. Does anyone know what model ignitor I might need. I contacted several british suppliers and they all seem to think I should use the LU-149, which as I stated, does not fit. Any help would be greatly appreciated.

Do your best to get the new version called the Igniter II. Better circuitry and NO worries about leaving the key on, no matter how long. You will have to mate it to the new Igniter II coil as well, but you should have done that with the early version anyhow. Even if you have to wait a month or so, it's the best one to buy. They may even be available for yours now.

The only Triumphs that Pertronix II is showing available for is the electronic ignition Spitfires and TR7s.

That's quite possible, Allan. I had heard that the new version for Tr3's and Tr6's would be available in the next 30-45 days, which is why I said that it might be better to wait a month or so.

Rather than has this out here... why not contact Pertronix directly about what is right for the DM2 dizzy? Their technicians have been very helpful and prompt the two times I've called them.

There are two kits for the DM2 dizzys. The LU-149 should fit the standard DM2. If your vacuum advance is attached to the points palte with a post rather than a spring with a loop on the end, then you may need a different kit. Is your points set held in place with 2 screws rather than 1 in this unit? If so, the LU-241 may be the right kit. If you can send me a digital pic of the assembly, I can tell you the proper kit! It may have non-original parts!

I just confirmed that your 1955 distributor probably does need the LU-241 kit. Does your points plate look like this?