T43 chassis mid-production revision?

[vanillagod]

Got inspired to try my hand at the sata mod from my prior thread here and was looking for a rougher unit I wouldn't be too devastated fubar'ing in the event.
While doing so, I noticed there were 2 obvious revisions of T43 chassis; applicable to both non-p and p models, even T42 from my scope of ebay search/ seller keyword spamming/ API recommendations.

From pictures alone, chassis are most notably distinguished apart by chassis bottom and right-hand screen hinge.
One revision had a flat/level chassis bottom and symmetrical "wide" screen hinges. The other had a "stepped"/ form-fit chassis bottom and asymmetrical screen hinges, "wide" on the left and "narrow" on the right.

At first, judging from production dates I had assumed the stepped chassis bottom model was later production but ended up finding later production with the flat bottom as well.
Was there any reason for this change? Is one chassis revision preferred over another?

"Flat/ level" chassis bottom w/ symmetrical "wide" screen hinges:
https://i.imgur.com/hO4odZo.jpg
https://i.imgur.com/07PfJhB.png

"Stepped/ fitted" chassis bottom w/ asymmetrical screen hinges:
https://i.imgur.com/1i3hiGa.png
https://i.imgur.com/iNvwTSf.png

[dr_st]

Your pictures stretch the page, so I removed the tags. Please use imgur's built-in "thumbnail" feature if you want to post large pictures inline.

To answer your question: this is not a mid-production revision; you are merely comparing the 14.1" and 15" chassis. The latter has the symmetrical wide hinges, the former does not. Same thing for T42.

[vanillagod]

Thank you for the help,
Are the motherboards on either size interchangeable?

[ajkula66]

Are the motherboards on either size interchangeable?

The motherboards are the same size so yes they are swappable between 14" and 15" units.

[kfzhu1229]

If you put a board into the 15" chassis though, be mindful of an extender that goes in the ultrabay or your motherboard connectors won't reach the ultrabay.
Also note while the keyboards look identical on the 14.1" and 15" machines they are not interchangable unless you rip the membrane and all the keycaps out of the metal chassis - the mounting holes are different. The keycaps and switches are though if you have the same keyboard manufacturer for both machines.
If you want the 15" version, I have just restored a 15" SXGA+ T43 but with intel GPU if you are interested.