ATI siren at the Army Heritage Center:

ATI siren by freebrickproductions, on Flickr

ATI siren by freebrickproductions, on Flickr

ATI siren by freebrickproductions, on Flickr

ATI siren by freebrickproductions, on Flickr

ATI siren by freebrickproductions, on Flickr

ATI siren by freebrickproductions, on Flickr

ATI siren by freebrickproductions, on Flickr
http://www.youtube.com/watch?v=gyl4ZI21AN8
Gettysburg:
STH-10 siren on E Legion Alley:

STH-10 siren by freebrickproductions, on Flickr

STH-10 siren by freebrickproductions, on Flickr

STH-10 siren by freebrickproductions, on Flickr

STH-10 siren by freebrickproductions, on Flickr

STH-10 siren by freebrickproductions, on Flickr

STH-10 siren by freebrickproductions, on Flickr

STH-10 siren by freebrickproductions, on Flickr
http://www.youtube.com/watch?v=RjfggEiTsDk
Sterling M-10 siren at 4th street and Water street:

Sterling M-10 siren by freebrickproductions, on Flickr

Sterling M-10 siren by freebrickproductions, on Flickr

Sterling M-10 siren by freebrickproductions, on Flickr

Sterling M-10 siren by freebrickproductions, on Flickr

Sterling M-10 siren by freebrickproductions, on Flickr

Sterling M-10 siren by freebrickproductions, on Flickr

Sterling M-10 siren by freebrickproductions, on Flickr
https://www.youtube.com/watch?v=DymjSFZ3Pus
York Springs:
Sentry 10v behind the fire department:

Sentry 10v by freebrickproductions, on Flickr

Sentry 10v by freebrickproductions, on Flickr
Eagle:
I saw a T-128 while I rode by on the interstate. No pictures unfortunately. Google Streetview Link. The Thunderbolt head has been removed since Google last went through there.
Highspire:
I was able to spot a Model 5/7 from the interstate. No pictures unfortunately. Google Streetview link.
Harrisburg:
I saw a T-128 next to a P-10 along I-283 and another pair to the east of Harrisburg near SR 283. Can't find either on Google Maps though.
New Cumberland Army Depot:
I saw three Whelens from I-76. I have only been able to find two. Locations of the two Whelens I was able to find.
I also saw another STH-10 mounted on the roof of a fire department, but I am not able to find it.