Got my parts truck in, making a little progress.

It's a 2005 Yukon XL with the 5.3 and a 4L60. The 5.3 is going in the truck, the 4L60 will be sold to fund a 4L80, the rest of it will be parted out. 

First order of business was to find out if it has a 24x or 58x reluctor, this will determine what kind of wiring harness I need and what kind of ECU. I jacked the truck up and crawled under it, but the starter is blocking the view from below. 

I tried looking through the passenger wheel well but you can't quite get a good angle on it. 

I tried from the top but the exhaust manifold was blocking my view. 

Then I remembered I had impulse bought a borescope on woot a couple of years ago. It was still in the hard case behind my desk. I broke it out and started digging for batteries. 

It even works!

Not exactly HD, but I'm still pretty sure this is a black connector, meaning I have the 24x reluctor, which is what I thought it likely would have. 

Now to decide on a stock ECU with HP Tuners or a Megasquirt.