I had begun to occasionally have trouble shifting into first gear (4.9L manual 4 sp. OD), but shifting was liquid smooth with the engine off, so I suspected the hydraulic clutch system. Upon inspection, I found that the slave cylinder was kind of loose-feeling in its mount, so I rotated the thick black plastic "c-ring" that helps hold it in place until it felt tighter, and put a dab of lithium grease on the end of the slave push rod where it contacts the clutch release lever.

I decided to "burp" the hydraulic system in case there was some air in it, so I removed the master cylinder cap, and crawled under the truck to push the clutch release lever toward the front of the truck a few times. I found that lying on your back directly under the master cylinder is not a good postion to be in when you push the clutch release lever forward!

Anyway, after cleaning my face (and the master cyclinder) and finishing the process, now my shifting is much smoother, no resistance encountered. I don't know if it was the repositioning of the slave cylinder or burping of the system that improved it, but it worked. I don't see any cracks or separation in the firewall around the MC, but I ordered one of the size small reinforcement plates anyway.

 

Brake fluid is just hydraulic fluid, it won't hurt ya.

Don't get it in your eyes, though.

It eats paint, too.

 

Somehow "eats paint" and "won't hurt ya" just don't seem to go together very well...

 

I understand.

Best for you to ask Google:

Let me google that for you