The question regularly comes up...which sound decoders are appropriate for which PRR locomotives?

Soundtraxx

British L-1 Class Tank (DSX #824214)

This is the "banshee whistle"/"freight whistle"/"single chime whistle".
A5 class
B6 class and all subclasses
C1 class
CC2 class
H class and all subclasses
I1 class and all subclasses (many converted to three chime passenger whistles after 1946) L1 class
L2 class

ALCO with WABCO 3-chime Airhorn (DSX #825211)

(Double check, entire series may be #825214 Wabco E2 single chime.) Alco PA1, PB1
Alco RS1
Alco S2, S4

ALCO with Leslie 3-chime Airhorn (DSX #825212)

Alco FA2, FB2

EMD 1st Generation with WABCO Airhorn (DSX #825201)

EMD E7
EMD F3
EMD SW9

EMD 1st Generation with Leslie S3 3-chime Airhorn (DSX #825202)

EMD E8
EMD FP7
EMD GP7

Fairbanks-Morse with Leslie S3 3-chime Airhorn (DSX #825242)

FM H16-44
What about the other "H" series locos?

Fairbanks-Morse with WABCO E2 single chime Airhorn (DSX #825244)

FM Erie-builts (Should be Leslie A-200, but Jack Consoli says this is closest available.)

Fairbanks-Morse with Nathan M3 3-chime Airhorn (DSX #825247)

FM C-liners

DSD-090LC Steam Micro Digital Sound Decoders

This line of miniature decoders was created with N scale in mind, but is also applicable to small HO installations as well. Each version has several whistles. The diesel versions are self-explanatory, as the "EMD 1st Generation" will have all applicable whistles, as will the "EMD 2nd Generation", "Alco", "General Electric", and "Fairbanks Morse". This issue becomes cloudy, however, with the steam locomotive versions. Here's the scoop on steam whistles, straight from Soundtraxx:

DSD-090LC for Light Steam Engines (#821101) includes:

British L1 Class Tank
C-16
4-4-0 light multi chime

DSD-090LC for Medium Steam Engines (#821102) includes:

Westside Lumber Co. Shay
DRGW 2-8-2, K-36 Class No. 484
East Broad Top, 2-8-2

DSD-090LC for Heavy Steam Engines (#821103) includes:

DRGW 2-8-2, K-37 Class No. 497
N&W 2-6-6-4, Class A
Frisco No. 1522 Mountain, 4-8-2

Gary Mittner notes from PRR-talk in 2000:

My drawings indicate the 3 Chime Whistle was installed on E5's, E6's, G5's, K4's, K5's, M1's, M1a-b's, Q1, J1, T1, I1's, I1sa's and N1s.

The Banshee Whistle drawing shows the following locos had this style whistle. Before I list them I will say it is hard to make out the whole list as the photo copy did not take very well. Hopefully someone else has this drawing so they can edit any mistakes I might type and missing classes. Class A5's, All B6 classess and subclasses, C1's, CC2's, All H classes and subclasses, L1's, L2's.