I needed to swap around parts to build a beige TI-99/4A console using a standard main-board, "QI" power supply, and a keyboard which does not stick. The original standard board came in another beige console which at one point in its life lived in a smoking household, leaving the case stained yellow by, and with a sticky layer of, nicotine, and the keyboard suffering from the same ailments -- sadly as it is not one of the crappy post-and-membrane types usually found in the in the beige consoles.
The donor case is from a malfunctioning "QI" console. Upon installing the standard board in the "QI" case I found the case would not close completely. I opened to inspect my work and found the board would not push into the GROM (cartridge) port trap-door assembly. After a minute or so of fiddling with the fit I discovered the problem.
The "QI" GROM port assembly has two posts extruding from its bottom which block the metal covering of the standard board.
The "QI" GROM port assembly on the left, standard on the right.
I did not try the standard board without its metal shielding so I cannot say for certain the board will not fit without it.
Something else noteworthy is the part numbers look very similar. Not knowing the way TI numbered its parts they look the same.
The part number "1015982 N" is molded onto the assembly. The "QI" assembly has a "7" floating off to the left side while the assembly for a case holding a standard board has a "5." As well, the "QI" part has "-04XX" seemingly hot-branded above and to the right of the molded part number.
Close-up of the part number on a "QI" GROM port assembly.