Why is one 340 connecting rod bronze color?

Max1196 said
View attachment 1715107441 The information supplied in post #35 has it's place in the industry, what that is all referring to is for use in the motorcycle or snowmobile engine manufacturing, where "surface hardness of Rockwell C of 60-63" needs to be achieved for use with "roller surface" type bearings.
What's going on here is simply put in post #25 a last attempt to be able to use a rod before it's turfed.

View attachment 1715107442

If that is a 1970 -75 440(RB) or 383-400(B) rod then chances are I ran it. I was working 14hour days 320 days a year back then. Forced vacation during changeovers to a new year car and some holidays off but mostly 7 days@ 14hours.(talk about a zombie) A good friend of mine worked the /6 rod line even longer and lots more hours until they cut the line and quit producing /6's