C2 exhaust manifold question

[Eugene B.]

Members,
Need to replace the passenger side exhaust manifold on my '65. The P/N is 3750556X. Question is: What does the X suffix mean? Date code is A6. Assume this means January 6. Front side also has a RH 6 on it. Any thoughts?

Seems like I can obtain a 3750556 without the X, but want to make the best choice. If it helps, the engine number is FO222HO and the VIN no. is 111,477.

Thanks gents and ladies.

Gene

[Gary B.]

RH 6 = Right Hand; mold number 6 *NM*

[Eugene B.]

Re: What does the X mean?

Gary,
Thank you for your reply. My question was what does the X following the part number mean?

Regards,
Gene

[David D.]

Re: What does the X mean?

Gene, I was told the "X" was used on some manifolds for mold checking, at the foundry. Dave

[Joe C.]

Need Known Original To Compare

Gene:

The TIM&JG states that there are no visible casting dates on original manifolds, but then has a chart showing date codes. I THINK that SB has no date codes, and BB has date codes, but I will not say that with certainty. The manual is very vague in its description.
My manifolds have "LH1" and "RH1" cast below the part numbers of the left and right side, respectively. They each have the 2 "teats" referred to under the BB description.
I hope I didn't confuse you even more, but you need to look at a KNOWN original to get all the details. I do not know whether mine are original or not.

Joe

[Mike E.]

Re: Need Known Original To Compare

Base motor small block exhaust manifolds had casting dates, high-horse (2 1/2) did not. That began in 1962 when the 2 1/2 manifolds were introduced.

[Joe C.]

That Might Be True, But.................

.........the TIM&JG states that "no visible casting dates should appear". This statement is found in the general description of "exhaust manifolds", and so should apply across the board. Also, the Manual is vague about any other marks which may appear. It only STRESSES those pesky "raised projections" on the upper seam of SB manifolds, to the exclusion of all else. I'm not questioning what you say above. There has to be a reason for the date code chart, but the Manual just doesn't give any. I only want to have a clearer description of an original.

Joe