The Rockwell 10 speed Downshift

are you flipn down before moveing gear stick?

 

It has finer teeth on the gears, so the synchronization between road speed and engine rpm must be closer before it will shift properly. Also, you don't mention which particular shift you are having trouble with, but if it requires the stick to make a lateral move, you can't "cut the corner" with a Rockwell and make a kind of diagonal move with the stick like you can an Eaton. You have to "square" the motion when going into and out of neutral or you'll never make it shift right. Once you get used to it, I think you'll like it though. It's just got a lot closer tolerances than the Eaton does.

 

They're very tough. I had several and after a few teething problems with the earliest production models, they were great. I should have asked you, what is the year of your truck? We had some shifting problems with the early ones when they got warm. The expansion from the normal operating temps. was enough to cause a bind in the shift fork. The solution was to double gasket the top cover of the transmission. That provided enough clearance that there was no more binding and the things shifted beautifully.

 

That's late enough that the shift fork issue should have been addressed. I doubt that is the problem....

 

I know this is an old thread, but back when I started driving i came out of a 94 FLD120 with a 9 speed into a 99 Century with the Rockwell 10. While they aren't as forgiving, and you must be dead on, it is still the best transmission I've ever used.
The owner's 92 had one she took drivers on road tests with to make sure they knew how to shift. I was possibly conceived in a truck as my parents both drove until I came along. So, while I can see how it would take some getting used to coming from an Eaton, and most people hated them, I never had a problem.