There is a modern 2x3/6x7 slide-in back, the Linhof Rapid Rollex. Note that this is not the same thing as the more common Super Rollex.

The Rapid Rollex was also made in a 4x5/6x7 version, which is more commonly seen.

If you can still find a new one it will be very pricey, but used ones occasionally turn up for much less.