Help with tranny problem on '77 305/T350

[baradonai]

Hi all.
I'm hoping someone can help with a problem before I spend a lot of money I don't really have. Also, I know just enough about car mechanics to be dangerous.

I bought the ole girl about 4 years ago from a guy in Alabama. It was a farm truck. She's a Blue 1977 GMC Sierra with a 305 V8 and what appears to be a T350 transmission. It's in fair shape for it's use and age but runs good. Perfect for hauling stuff on the weekends.

Weekend before last I decided to replace the valve cover gaskets. They were older than dirt an leaked alot.

When I was finished, I noticed a green wire had come loose from somewhere. Couldn't tell where it was supposed to go. It comes out of the firewall on the driver's side




There's also a hose on the back of the carb that goes to nowhere and a nipple above it that has nothing on it. Don't know if I knocked something off there or it came that way.
http://67-72chevytrucks.com/vboard/a...1&d=1319034068

The biggest problem, though is that it no longer goes into any forward gear. Just reverse. No grinding noises. Nothing seems to engage going forward.

Originally I thought, great! the transmission has finally gone out. But then after reading some posts here, maybe I hooked something up wrong on the vacuum or the green wire has something to do with it.

I moved this thing when i replaced the valve cover gasket but didn't remove it. It looks like maybe this is a vacuum line that goes to the transmission.
It hooks into a tree like adapter on the front of the intake manifold.
If this was bad, would it prevent the transmission from engaging? How would I know it was bad?
http://67-72chevytrucks.com/vboard/a...1&d=1319034723




I've posted pics.

Thanks in advance for any help and advice!