Diaphrams for Alco PA ABA's

You might try to get some of the K-Line ones they might work or try one of the 2 rail scale suppliers.  I think I read on one of the thread of some done in a fabric which would be more prototypical.

I used the Keil-Line folded ones that you put together, for my E 6's. The easy route would be to find the molded black rubber ones, just depends on the look and purpose you're going for.

Weaver has diaphragms on their website, I have used them for both passenger cars and some diesel locomotives. I use rubber cement to apply them. 

chck out the recent Classic Toy Trains magazine.

they have an article about that very subject

and how to make your own from

inexpensive materials.

Although all the cab and booster units from all manufacturers were delivered with blind end diaphragms, they fall out of favor beginning around 1960 and one road after another removed them.  I can recall seeing them still in use on SP passenger and freight units during a trip to San Timoteo Canyon in 1957, which would be the era of your Daylight color PA's.