BB-61,
Is there a list of foundries that made the M60 hulls?
Here are the foundries that made hulls and turrets for M60 tanks.
General Steel Castings Corporation, Eddystone Pennsylvania & Granite City Illinois.
"G" inside a Shield. They made both Hull and Turret Castings for M60, M60A1, and M60A2. Any M60A3 with these marks are rebuilt from A1. The hulls made by them were one piece, or as close as you can get to it since the floor plates were welded in. They also used the prefix "GC" with the casting series number.
Continental Foundry and Machine Company, East Chicago Indiana.
Continental Foundry and Machine Company, Wheeling West Virginia.
Continental Foundry and Machine Company, Carapolis Pennsylvania.
"C", "P", or "W" inside a "C". Continental made the majority of the Hull and Turret Castings from their three foundries. These hulls were cast in separate sections and welded together. The sectional hulls can be ID'd by a vertical weld seam along the side. After 1974 the rear hull was cast in two pieces and can be ID'd by the vertical weld seam bisecting the rear below the grill doors. Blaw Knox eventually owned Continental but they retained the same cast ID's. On occasion some of these sectional hulls will use castings from more than one of Continental foundries.
Union Steel Castings, a Division of Blaw Knox, Pittsburgh Pennsylvania.
Keystone with "U" inside. Turret Castings only to my knowledge.
Pittsburgh Steel Foundry Corporation (PSF), Glassport Pennsylvania.
Circle with a "P" inside an upside down star. This mark is found on early M60A1 turrets. They also made gun mantels and were marked with "PSF" instead of the star symbol.
There is much more to this but it could fill a chapter in a book and get pretty boring to most .