Originally Posted by Powerstroke Cowboy
6 speed trasmission, 6 Speed clutch and flywheel for 99-03, a 99-03 slave cylinder, You will need a 6 speed transfer case with a 24 spline input shaft. you will need to take the 5 speed trassmission spacer out. 6 speed will not need it. You will have to pound on some sheet metal to make it fit. make your drive shaft shorter and lenghthen you 4x4 shaft. And get a six speed stick. That about covers it
What he said.
Why exactly do you want to go to the six speed? In the end, the total range of gear ratios (1st/grannygear vs overdrive) is nearly the same in the 5 speed vs the 6 speed. I wanted to do a six speed conversion (before I realized how involved it was) when I wanted to drop highway RPMs for fuel savings. In the end however, the 5 speed would basically give me the same gear ratio has the 6 speed in the top gear.
Consider this too: these engines have ample torque to deal with the larger gear ratio jumps in the 5-speed, and larger gear ratio jumps means less clutch use, less clutch use means fewer times that you'll be doing what you're doing now and replacing clutches (which are a bit pricey).