You're asking the wrong guy about lifting it,i live where every guy and his dog has a lifted 4X4 and i can't stand them,lol. As stated you're opening up a whole bunch of issues that can occur with lifting a truck with that many miles on it,especially in the rust belt,and a 6 inch lift with 37's is hard on your front end components,plus makes the truck a whole lot slower,and burn way more gas.To pull 37's with a 6 speed,you'll want to regear it to probably 4.56's,which means you need to swap your ZF front diff for the earlier AAM/corporate front diff,as you can't regear your ZF front diff,and that means finding all the pieces needed to bolt the older diff into the truck. I agree with the other guys,instead of spending money modding it,put that money into paying it off faster,then buy yourself a daily driver ,that way you're in a better position to mod it,as you can still get back and forth to work while you work on the truck. Modding a higher milege vehicle that you're still making payments on,and you need it to get back and forth to work,will eventually bite you in the rear.
We've all been young,and i don't blame you for wanting to mod it,but you have to face reality to
If you want my advice,pay it off as fast as you can