no third gear

Robb when it's in the most forward position and it goes into 2nd quickly it should go into 3rd real quickly also. Unfortunatley I haven't ever worked on a slant 6 linkage setup so I'm unfamilar with exactly how thair setup so I'm not sure on the last question. I do know there is allways a spring somewhere that pulls the linkage back forward.

I'd say next step is to check the band adjustment. The front band is the one to be mainly concerned with and that's the easiest to get at. You don't have to drop the pan to get to it. It's on the drivers side right above the linkage. Your Haynes book should show how to adjust it. Just loosen the locknut and tighted the inner screw to 72 inch lbs. Then back it off 2-1/2 turns then tighten the locknut making sure the inner screw dosen't turn.