after i put the new one in the hotter it gets the harder it would shift. i put a oil cooler with pump and t-stat keeping it at 160 and it has been all good from here on out.

 

I put Royal Purple's fluid in it, and it shifts like a truck; however, It does always shift. Try blipping the throttle when the clutch is in while shifting.

 

I have about 55k on mine, have not changed yet, maybe around 60k. Bought new. Shifts fairly easily, although it takes time for the synchros tod do their job. Sometimes it shifts faster than others, depending on how the gears line up at what rpm. It downshifts fairly easily, although I usually wait until 1200-1500 rpm, or less. My biggest problem is getting it in reverse. Sometimes I have to try a number of times and try other gears before reverse lines up. I try not to man handle it, as that probably does more harm than good.
I agree it is absolutely necesary to srick with a flid blended and specicly reated for this trany, or kiss your synchros goodbye.

 

I have a 2002 with 6spd, sometimes difficult to shift into 3rd, often it is difficult to downshift. When I shift without the clutch, appears smooth, obviously I am not attempting to downshift.

 

To ease the feel on downshifting try touching the throttle to rev it up a little, this makes mine go in almost effortlessly. I never downshift into 1st until I am almost stopped.
There is a ton of rotating mass in these boxes so you need to be patient when shifting.
Trouble getting into reverse is a good sign of worn blocker rings. Sometimes double pumping the clutch or letting the truck roll just a little bit would help mine drop into revers before I got the rebuild.

 

Do not shift without the clutch. It is a synchronised transmission and clutchless shifting will cause dramatically increased wear on the synchroniser blocking rings which are little brass/bronze/fiber clutches that prevent grinding of the gears.

If in doubt do a search and you can see what I have to say about this, as well as the abundant uneducated arguments to the contrary.

 

I dont think reverse has synchros

 

4th gear has like a 5mph window to downshift if you dont blip the throttle. 20-15mph Same thing with 3rd. You can shift into 3rd from 15-10mph. If you want to shift into those gears at a higher speed you have to give it some throttle with the clutch pressed in before it will pop into gear. Personally, I think its kind of a pain with a dual disc, so for 3rd and 4th I just do the former