Just replaced the radiator on my '94 5 spd with a/c. The new one is a single row plastic and aluminum auto trans spec. While it's only one row, that row is at least twice as large as on the old radiator, about 3/4 in. or more. I'm really impressed by the quality and fit of this radiator, it's a Koyo A1140. I got it from
1140KO. You have to specifiy the KO, the first one they sent me was an all metal unit. They were very nice about letting me take it back to their local distributor and exchanging it. I definitely would order over the phone, not online, so you can specify exactly what you want.
Hope this helps someone,
John ('94 Miata)