OldIHC

I have a speedometer adapter for the 2 speed axle I dont need. It was on a gauge cluster I bought for parts. I cleaned it up and there is no visible damage; the rubber boot for the vac diaphram is intact. $40 and I'll cover shipping to the lower 48. International may be more.

Allen

I bought a NP205 transfercase from a Travelall. It had a two speed speedometer adapter on the transfercase. I do not think I have the adapter now. Interesting stuff.

I don't need it, but someone else may want to know- do you know the ratios of the two speed axle of the truck it came from? For the speedometer to be accurate in both high and low speeds, the adapter needs to match the axle.

Dean

Unless it came from a very large truck with a Timken (Rockwell, Meritor now) axle the Eaton planetary design used in most trucks with two speed axle all use the same ratio between low and high. It has to due with how much room and a how small you can make the planetary section and fit it inside the ring gear.
It is why all modern electronic speedo's with the 2 spd option are set at (I think, I may be off slightly) .775:1.
The Timken designed two speed axles use a spur gear primary reduction with two different ratios that can be close (like the Eaton) or wide, as the two speed section is not inside the final reduction but housed either on top (for top loading) or in front (for front loading) axles.
Most every adaptor like that will be for the close (Eaton) planetary rear axles.

I dont know what truck it came off of. It was attached to a K/KB speedometer in a cluster identical to my KB1. I just needed the speedo face and temp gauge. I found some numbers on the housing. They appear to be 675CDS3, (or very similar). Also found a patent # and "Stewart Warner" if that helps anybody.

Allen

Extremely few trucks fitted with two speeds, would have a two speed with a wide ratio axle, I would be surprised if they would exceed 0.1% of the two speed trucks produced. All other take the same adaptor.