[Rick Parker]

The trigo adapters have a 3/8" base with the threaded portion machined from one piece of metal. It will without any other modifications increase the track 3/4" of an inch overall but as mentioned above can be allowed for by machining from the back of the wheel.
I used Trigos blank (undrilled) adapters and mated them to PS Engineerings FIA wheels on a narrowed 9" all to keep the wheels and tires under the car to achieve the proper "LOOK" that we all strive for. The pad that is on the back of the FIA wheel will only allow a 6 pin fitament (no 5 lug) and I was concerned that the original 1/2" diameter drive pins with 3/8" threaded portion were questionable (unfounded at this late date). When ordering new axles I hade them drilled for 6-1/2" studs (stronger) on a 4 1/4" circle and when mated with the properly machined adapters and 6-3/4" barrell nuts that hold on the adapters themselves make for a great bulletproof combination, Far stronger than the original cars and providing for a larger surface area to actually drive the wheels themselves. When I was in the design and planning stages of this and speaking with Phil at PS Engineering he had not previously done this combo but it has worked out perfectly.
The Halibrand style wheel WILL allow for a 5 pin fittament because of the larger mounting pad on the back and their spoke design. That is specifically why they are so popular in this application. The Trigo adapter is very similar to an original car except the oeverall diameter of the adapters themselves are intended to match up to the diameter of the axle flange on a typical live axle and after fitting they can be reduced in diameter if desired. Lynn Park who owns Trigo is well versed on any type of wheel fitting desired on a Cobra he usually answers the phone himself.