what locomotives were used at PRR's Alliance Ohio station

Start looking for prototype information on line.   There are many sources and quite a few with historical photos. 

Also consider joining the Pennsylvania Railroad Technical and Historical Society - PRRT&HS.    They have a website that has information and members have access to the archives at Lewistown PA.    Also they put out a very nice quarterly magazine and host annual conventions that are well run and have very good presentations generally. 

I think Alliance is/was on the PRR Ft Wayne Mainline from Pittsburgh to Chicago.    So I would guess most any PRR loco would have been seen there at least passing through with the obvious exception of electrics.   And since is the Ft Wayne main, the very famous Broadway Limited would have run through there.    M1, M1a, J1, I1, N1, N2 K4, variouis H classes etc are all possibilities along with the duplexii in late 40s.

@3 time modeler posted:

. . . I have just discovered that I have a Great Uncle, who hired on with PRR as a fireman on 12-29-1899  and was promoted to engineer in 2-1903 . . . I think he was a member of one of these divisions: 219, 574, 630, or 299.

The unions representing Locomotive Firemen (Brotherhood of Locomotive Firemen and Enginemen) and Locomotive Engineers (Brotherhood of Locomotive Engineers) used the term "Division" instead of "Local", for their local organizations of their membership.  Where a truck driver might belong to something such as Teamsters Local 123, an Engineer would belong to something like BofLE Division 660 or BLF&E Division 398.

You can find historical lists of the Division numbers of the railroad unions, online.