Having owned a 92 with leather seats, I am unsure.
I am fairly certain that they were put on by the dealer. The leather is different from the 93-94's I have seen.
FWIW, I liked the ones in my truck, They were so much easier to clean than cloth.
Having bought a new 1991 in 1991 from the dealer, I can tell you leather was not a factory option. Doesn't show it in the 1991 factory brochure I have. Some dealers did install leather as an aftermarket ad on.