They do make a 2-band preamp, STC-2. It also has the slap switch. They used to have the STC-2M version which had a different bass control frequency. I don't see that listed anymore. I installed a bunch of those for a certain customer I had in the past.
As with most of these aftermarket preamps, they are not based on the real Stingray preamp, but probably have similar crossover points on their tone controls.
The real Stingray preamp is a rather unusual circuit and uses an unusual op amp. They have a particular tone. I tried some of mine with my pickups, and even though my pickups don't sound like MM pickups, the preamp added some of that bite.