Interesting question for Jason and Russ or anyone who KNOWS THE ANSWER.

At the moment, i'm giving the Fleetwood a service and found this. (never spotted it before)

On my right side chassis rail, facing the transmission, maybe an inch or two behind where the filler tube for the auto is, I have 40 stamped on the rail.

Its been done with letter/number stamps.

My first thought, was it was a code number for who welded the chassis up, however, my chassis markings for the chassis folks are up the back of the car and very easy to read, so no reason to stamp 40 where it is.

My second thought, was did it refer to a extra bracket or different brace to suit the T400 trans?

You would think though, T4 would be better than 40.

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Keep ya shirt on Fart Blossom.... LOL :-)

Its still friggin dark here, you know, down under.

I'll grab a photo soon. Its funny ya know, when you lie under a car on a mechanics creeper here in the southern hemisphere, it feels like you are in the northern hemisphere, because.... well..... um.... shit, forgot my meds this morning.....ahhh, better, now, what was the question again

I would suggest, it was stamped before assembly, as the "40" is really clear, and straight. With everything assembled, it would be a right turd to do and get it done clean and clear with one go. 

Could it be the IQ of the owner?   ;-)

Holy Shit Anders, my IQ only rolls in at 28 and a half. (I scored an extra half point for spelling my own name correctly)

OK, the plot thickens..... there is a 40 stamped on the opposite frame rail.

Then, near the exhaust flange on each side, it has "30" stamped on the rails. I'll pop up a pic of what mean shortly, I need Astrid to load the pics for me. Told ya I have an IQ of 28.5.

OK, this is "40"pic near the trans. Over to the brains trust now.

OK, the fact  I found a "30" near the manifold flange areas of the chassis, tells me if I went back along the chassis to the rear, I would find "50", "60" and so on?

that's not a forty, it's a minus 40.  
two ideas that are pure speculation:
first, if the stamps are aligned with the body mounting tabs, they may be markings made by the frame supplier for variances, so that  GM workers will know how thick the washer shims need to be when they install the body to the frame.

second theory, is the stamps are jigging marks.  The frames were made by AO Smith Co. on a jig, which was basically a bed with dowel pins, unto which the stamped pieces would be placed for alignment during assembly and welding processes.  The holes in the frame they would use are then used for measuring in chassis repairs, and are listed in the shop manual as tram points.    It could be that those marks are for dowel pin offset, telling workers to how to adjust the dowels in order to keep the part in perfect alignment with other pieces once fully assembled.  This would allow makeup for the variance or wear in the stamping dies that made up the pieces , or shrinkage during welding of the individual subweldments of the frame.

all of this is pure BS, but it seems like it could be right.  

sounds ok to me..... any other thoughts?

I'm thinking Mark got it nailed (again). Section 3. Frame in the book might be helpful to determine this question.



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