Physics Integrator in Torque

I could have sworn that I asked about this on Sunday, but I must have thought I posted it and did not.
Anyway, is the physics integrator in Torque a Euler integrator? Has anyone tried throwing RK4 in there? I read an article that talked about how RK4 is generally more stable and does not lose accuracy as quickly as a Euler version. This was a game development article and I was curious as to what Torque uses. I found some code snippets on RK4 and I was thinking of experimenting with this.
I have been playing with the physics of a hover vehicle to try and understand how it all works. I was able to get a spring with dampening working to control height against gravity. I also swapped that out and used a PID loop to get a similar effect. I am planning on changing the drag to get more snappy response. For now I am just playing. I hope to create a vehicle that will be fun to drive for a game I want to make. Basically, it would be a very simple terrain follower with enough physics to send it tumbling once in a while.

Thanks,
Frank