Waterjet options for 2 inch thick aluminum

I have a project where I need an internal gear and external gear cut out to make a drive coupler to match an engine to a transmission on a wheel loader.The internal gear is 12 1/4" major diameter with 72 teeth that are straight cut like a giant spline and the outer gear is about 17" diameter. The old coupler is 1" thick to engage the male gear.
What thickness of aluminum can a waterjet cut accurately and with some economy?
I could get by with 1 inch thick but would prefer 2 or 3 inch thick.
The way its done now is the internal gear is cut right into the engine flywheel and the starter ring gear is also used to scavange the oil out of the bellhousing and lift it up to a gravity drain back to the transmission sump. I want to put in a different engine that needs a housing adapter to mate the two. The aluminum drive adapter needs to be bolted to the new engine flywheel with appropriate spacer and piloting. This is a 100 HP diesel in a 18000 pound loader.

Do you have the waterjet machine ?

Wire EDM might be a better choice.

I dont have a waterjet, I got a few old manual machines and would have to hire this piece made.
I didn't think of wire EDM, If that is a better way Im good with it.
There is a waterjet machine in town but found they are too busy with their own work.
Don't know of any EDM shops.
Thanks Wingit

Cutting 2" alum. is no problem for a "good" waterjet. I have no experience with EDM but I'm with Doug in thinking that it might
be a better choice--slower and more costly but damn those things can cut accurately. You "might" get away with a single cut
to make both internal and external parts--there wouldn't be much clearance between them...

One question, though........why aluminum? Seems like it's gonna wear and get sloppy pretty quick. Wouldn't some sort of
steel be a better choice? If you're running metal to metal you must not be concerned with damping or cushioning so some
sort of steel is gonna last a lot longer...

The original flywheel is cast iron which is the Female part and the Male gear is steel. Given the low Horsepower and Large size of the coupler I think Aluminum would be fine plus I would like to keep it as light as possible because of added weight and overhang on the Flywheel. This is a wet bellhousing so there is not the rust/fretting problem dry couplings often have. The original flywheel and gear have no wear in about 12,000 hours. I only need the Female side of the coupling.
Thanks