Go to Sid's www.droppedaxles.comThat is the best advice you will find period. Sid is on the HAMB often.
You can even have your own axle dropped, then you know it will bolt right in. Sid will walk you thru everthing you need.
There is no drop spindles available for your truck.
Mono leafs will drop it more, however not required.
I would invest in a disc brake swap to increase the braking
Now if you had an AD, I would consider selling you an IFS kit.