I would want both brake chambers to match original equipment.
No. It's both a bad idea and a violation.
Brake wheel cylinder or axle sealBrake wheel cylinder or axle seal
Typically used on the steer axle, but sometimes on drive and lift axles (especially ones with single chamber brake cans). They allow the air to charge into and evacuate from the brake chambers rapidly.
The adjustment is on the back of the rear hubs. Below the axle tube is a hole with a black rubber plug in it. Remove the plug and use a brake spoon to adjust the star adjuster.
They have two chambers - a service chamber, and an emergency chamber. These will typically be T30 brake chambers (as opposed to T20 brake chammbers used on steer axles, the #3 axle on International Prostars, and the Kenworth T2000, and on wedge brakes). Inside the brake chamber, there's a spring that, when decompressed, turns the S-cam (or flat cam, although those are a bit rare) and effectively engages the brake. This is your parking brake. When you supply air to the emergency chamber, air pushes against this spring... when that air pressure is 60 psi or higher, it exerts enough force against the spring to compress it, releasing the brakes.
The air is held in tanks near each axle Air is put into lines from the "Service Valve" under the Brake Pedel. It rushes to a valve called a relay valve mounted very close to each axle and each brake. The air from the service valave causes the Relay valve to send air from the tanks to the brake chambers causing the brake chamber push rod to move.
Trucks with air brake systems have them on the steer axles. Trucks with steerable pusher axles usually have those... non steerable pusher and tag axles (the difference between a pusher and a tag axle is that a pusher is located in front of the drive axles, and a tag axle is located behind) can go either way... they might have a single chamber 20 can or a dual chamber 30 can. Some trucks also only use dual chamber 30 cans on one drive axle, meaning only one axle has spring brakes... I see this often on the International Prostar, but have also encountered it on some Kenworth T2000s.
An air brake system which uses foundation drum brakes will have one slack adjuster per brake - two per axle. They'll be located inside the wheel well - the slack adjuster is will be located at the end of the pushrod which extends out from the brake chamber.
You have to remove the center of the axle plate and the axle to remove the brake hub.
It all depends on what part is leaking what fluid. Brake cylinder would leak brake fluid. Axle seal would leak gear oil.
step on the brake
Axle has a short "a" sound: "aksel"
A typical tandem axle tractor has 6 brake chambers.