Rear drum brake cylinder cup expanders

[Dino]

Even though I have a '69, the entire drivetrain is out of a '71 police car.  I'm not sure if the rear drums are as well.  I'm trying to figure out if the brake cylinders in the rear have cup expanders or not so I know if I need a residual pressure valve in the rear line or not.  How can I tell?

[b5blue]

Take one apart. I really don't think yours could be so old you don't have them? I replaced rear wheel cylinders 3 times in 20 years just as standard service overhauling for a daily driver. 

[Dino]

I don't know when they started with the cup expanders.  You think these would have them?  I'd rather not take them apart, the rear brakes are fine and I'd rather not have this snowballing into something bigger.   

[b5blue]

See the rings on the end of the springs...that's them I think. The complications of plumbing more crap needlessly is what I avoid. New cylinders are simple and less money to boot. Heck the seal kit costs more than a new cylinder. 
http://www.autopartswarehouse.com/sku/Dodge/Charger/Centric/Wheel_Cylinder_Repair_Kit/1970/CE144-dot-64012.html?apwcid=gglpla&gclid=CJCD18GohsoCFdU2gQody8ADlQ

[Dino]

Okay so the best way to go would be to check the current cylinders and if they don't have the cup expanders just get new cylinders?  Do all the new cylinders have the expanders?

[John_Kunkel]

If in doubt, install the RPV.

[b5blue]

Okay so the best way to go would be to check the current cylinders and if they don't have the cup expanders just get new cylinders?  Do all the new cylinders have the expanders?

Standard for many many years! The slaves can be installed with much still attached, I've done it. (Best to just clean and service so you can lube the backing plate rub bumps for the shoes also.)  I know...more work! 

[B5 Charger]

For what it's worth I've rebuilt several Mopar wheel cylinders over the years from 1964 to the mid 80's.  They all had the rubber cups.  My guess is yours does too.  To be honest I thought that was the only design for them.  Is there something different?   

[b5blue]

"Expanders" push the edge of the rubber cup outward to hold sealing better. 

[John_Kunkel]

Only a physical inspection (remove, disassemble) will determine if it has expanders or not, most smaller diameter kits don't have them but some larger diameter kits do.

[B5 Charger]

Ahh, not familiar with expanders evidently.  They are the little metal inserts that go behind the rubber cups?  Never ran across those I guess.