ummm... did my clutch rust together or something?

[SeanPaintsFlames]

So, I got my '83 K10 (9" lift, 38.5 Thornbirds) up to the axles in sticky mud twice over the weekend. Then I pressure washed about 4 inches of mud off the bottom of it, taking about and hour and a half. It started raining towards the end of the clean up, so once I was done "enough" I took the truck for a drive around the block to give it a last rinse. Today I get in it to go to work and the clutch feels stiffer, and it won't go into any gear but 4th, but only then with pressure. I was able to start it in reverse (with the clutch to the floor, even) to get the starter to scoot it far enough out of the way so we could get my wife's truck out of the garage.

What have I done?!?! What can I do to fix it?