It is indeed torsion bar based front suspension. For a little bit I ran the truck with cranked torsion bars, and it raised the front end about an inch and a half. I backed that back down to stock when I noticed noises coming from the front end. Not good.
I’ll look into different torsion bars and keys maybe. The problem I’ve always heard of is there isn’t all that much room for adjustment because of the steering/suspension geometry. Hence the noises mentioned above.
I forgot to mention that this truck has a whole bunch of heavy duty RPO codes in the glove box: F44, brakes, radiator, oil/trans cooler, suspension, a few other things. It’s basically a “heavy” half ton.
Also, my dream would be to do a solid front axle swap. It really is a dream, though. I don’t think I have the knowledge or skills to do that. I have access to a 6BT Cummins with an Allison transmission, but that would be way out there. Huge job and almost certainly beyond what I could do. And I would need some Dana 60/80 axles front and rear. Definitely a dream.