Having hard time determining spline count of steering gear input shaft
 

I want to assemble a new intermediate steering shaft in my engine bay. I don't like that old rag disc setup. I'm doing this with a telescoping shaft and two universal joints. The shaft and firewall end U-Joint is no problem.
But I am having difficulty selecting the correct U-Joint for the steering gear box input shaft. I tried a 3/4DD X 3/4-36 spline coupling. But it didn't fit. Fortunately I got a full refund.

I tried counting the input shaft splines with the steering gear in place in the engine bay. I guess I did not count them accurately. It doesn't make sense to me to remove the steering gear to count splines. Can a 12-point socket be inserted over the
steering gear shaft to determine spline count? Does the steering gear have any number tag on it to help me narrow down spline count?
The splined opening of my old steering shaft has 15 splines, a flat, and the rest of it looks relatively smooth with very shallow grooves or 'stripes.' But can this be used to determine the spline count of the input shaft?

This is the only thing holding me up. I tried researching this. But I just can't be certain of what the spline count is. I have a 92' Ranger XLT 2.9 V6 with power steering.

I have a couple possible solutions for this. I'll try to take a close-up picture of the input shaft with my smartphone camera. I did this on another part of the truck, and the detail was fine enough that I could count all the splines.
Or I might make an imprint of the splines with a soft, pliable material.

Still working on this. The problem is the U-Joint that connects to the steering gear input shaft. I tried two different U-Joint sizes and both did not fit.
I also used modeling clay to make an imprint of the spline count.

I might have to completely abandon this upgrade. I simply cannot find the correct fit universal joint to mate with the steering gear input shaft splines.
I tried 3 different U-Joints now and I had to return all of them. There might be a way I can cut off the old steering shaft splined end and have someone weld it to a new U-joint coupling.

I have heard a couple reports of people filing down new splines to make it fit. But I'm not willing to take that chance.