This is a silly argument.
A lot of people who are active here drive older trucks, hence the general answers, but there's a wealth of info available across years:
"The 2001+ Ford Ranger gets its raw speed signal from the OSS (Output Shaft Speed) sensor located on top of the transmission (not on the transfer case)"
So yes, apparently on '01+ it is before the transfer case. If the speedo on these trucks is correct in 4low, I assume the computer was smart enough by '01+ to correct for being in 4low.
I would not assume the article is wrong, conventional understanding is wrong, the OSS is unrelated to the speedometer, and every truck '98+ uses the RABS sensor and no-one ever
