Swap a 5/4 tranny out.

[madmax]

I know anything is possible with $$, roughly speaking is it a major deal to pull a 5 &4 out and install something like a 15 or 18? I need the low gears, but dont really trust anyone else driving the truck without tearing something up in it...LOL.

[mike in idaho]

Just pick out the one you want and bolt it in. You will need a different driveshaft, of course, and will need to mount a carrier bearing to support the center of it. A shorter speedo drive cable and an air line to the back of the trans and you're in business.