20k steer axle

It might have some stops on it you can adjust or take off and get a sharper turn radius,make sure your tires don't hit the frame when turning all the way if you take them off.

 

In’99 my buddy speced out and purchased a new 379 with the standard track setup (same as yours with the hydraulic assist). He was adamant about having a TRW steering gear instead of a Sheppard. That 260” wheelbase truck turned pretty dang sharp. I’m not sure if the gear itself had alot to do with it or not.
I had a 230” 379 with a Sheppard and a 260” 379 with a TRW. I slip seated these two at the same time.The longer truck turned sharper (2002 and 2003 year models respectively).
When I speced out my new 389 in 2013, I was adamant about a TRW steering gear. They wouldn’t let me have it and ended up with a Sheppard. My 389 has the wide track front axle and it turns impressive sharp.
All these aforementioned trucks had the bumpstops adjusted past the factory settings ( my 389 tires actually hit the gear/pitman arm if I lean too hard on it).
If you have a Sheppard on a standard track, you might have the same problem as my 2002 379.
My buddy’s 379 is the only aforementioned truck that has the 20k hydraulic assist.

 

So are you running out of travel on the cylinder or the gear…usually with stops removed something hits pretty good
I assume you have at least 385 tires maybe with 315s nothing would hit

 

This stretched day cab will not make a u turn from one side of a 4 lane divided state road to the other. That is not a problem because we are not allowed to do that anyway, right. I bought it this way and just learned how to drive it.
It is a set forward axle. The set back axles turn a lot shorter turning radius.
Most times I tried doing things like you are taking about I ran into problems. Springs are different width, spring hanger off set is different, Neither of the drag links will work etc. Think long before you jump into swapping parts around.

 

Shoot a pic of the profile of truck, do you have the forward or rearward axle version, that will change a lot more than you may think in your perception of how it turns. Ive driven forward and rearward steer axles on both petes and kws amd the rearward steer ALWAYS *seems* to turn tighter than the forward steer even if the wheelbase on the forward is shorter

 

With the wheels pointing straight ahead take a picture of the pitman arm and drag link from the side if possible.

If the box doesn’t have enough travel you might be able to put a longer pitman arm on…I did this on a ford with 20k from and a steering box on both sides