Where on the M60 is the SN stamped?

Might be a strange question ("on the receiver dummy!") but I recalled that receivers were available to military armorers as replacement parts and it made me curious enough to ask.

Here's an archived answer...
http://www.ar15.com/forums/t_6_22/381638_M60_receiver_question.html

With most Military Contractor MFGed Guns (SACO/Lowell/Maremont/New England/etc.) generally the serial number is on the trunnion from what I have come across.

The next largest group of guns out there are the RIA guns.   The majority of these the Serial # is on the sheet metal, but as referenced by the thread from FALDOC above, some earlier RIA guns were made with trunnions from demilled ex-mil guns so you could see a serial on the trunnion and/or sheet metal.   The later generation RIA guns with their own mfged trunions are just marked on the sheet metal (both maker and serial) and the trunion is clean of any markings what-so-ever.

I am sure there are aftermarket guns made by various C2s out there that have marked some combination of the trunnion, channel, or left/right rails.  (never heard of the rear bridge being marked before but I guess it is possible)

I my day, didn't touch M60's.
Even I, as a Small Arms Repairman had to send it to Depot Maintenance if the trunnion became loose.
Serial numbers were on the trunnion.

Many thanks for the answers, and my appologies to Faldoc. My google and search-fu is apparently weak.

Most MG's have a specified part of the receiver (for example, the right side plate) that for registration purposes is "the gun" and on which the serial number must be placed. The M60 is unusual in that the whole receiver assembly (a permanent assemblage of parts) is "the gun" and theoretically the serial number could be anywhere on this assembly. The individual parts of the receiver are not generally meant to be replaced, but in fact they can be, and are.  This is going to be a more often-encountered issue as people want to upgrade their 30-year-old M60's to the latest configuration.