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The sensor could even have some smarts in it. The factory crank sensor reads 2 signals and outputs 1. The stock crank trigger wheel is like 2 doubled up. Whenever the front wheel is high the rear is low. The sensor measures both and so long as they are opposite it outputs a pulse.

Quick google search looks like the cam trigger wheel does the long pulse. Raised section is half way around the wheel.

that doesn't make sense though because the magnet in the cam wheel is like 10mm in diameter max, it passes the sensor fro no more than 20 degrees I reckon ....

Picks I found are a raised section half way around the wheel not so much a casting on the cam. Hope that makes sense. I've seen a crank shaft wheel in person but never a cam wheel. I'll get a screen shot and post up.

see the magnet, its in a black plastic bit that clips into the cam wheel

Google images this. Wonder what it is off just said LS1 think it was LT1 swap.
The US seems to of got some different combos to us.

yeah that's certainly very different to the V6 one above it!

Ah V6 yes the old "low res mode" they're different that's all I know.

yeah but if you just want a cam sensor for home reference surely that's enough ?

Couldn't be sure. Looking at the trace from GM in the V8 manual it's on for a fair time. And I read on Google somewhere (not official GM literature) that when doing a crankshaft re learn it knows from the crank patter where cylinder 1 is and if the cam pattern is reversed the code can adjust it's calculations.
But that is with the full 24X crank pattern. Low res V6 is 3X crank and 1 cam I've never seen the trace for that though.

Is that pic of yours a V6 fitted with a 0411 PCM?