help with 1970 c-10 tranny please....

[the12catlady]

i have a 1970 c-10 pickup with 3 on the tree.
a few days ago while driving it the gears jammed - no big deal, used to do that all the time before i switch steering columns. pop the linkages out and all i can get it in is 2nd which got me out of the intersection and into the drive way.
but my shift linkages under the hood just flop back and forth together and i KNOW they didn't used to do that. i assumed it was the column since i'd had problems with it before and i switched it out. the column looked fine when i got it out and the new one didn't help.
then while trying to shift it through the gears, the transmission siezed up and you couldn't even shift it from the levers on the transmission. acted like it was in foreward and reverse at the same time.
jacked up the back wheels and turned them to pop it loose and shift the gear levers on the transmission,which it will do now, if your carefull, and under the truck shifting the levers on the transmission.
the long arms that go from the transmission to the top linkages are loose and have too much play at the bottom - they need a new bushing - but they have for years, and they don't look any worse now.
the transmission was just rebuilt less than 2 years ago, but i was hearing some noise from one of the bearings that the mecanic said he would replace, but was dragging his feet on.


anyone have any sugestions as to what happened and how to fix it? i'm thinking rebuild the tranny... but i don't want to do that just to find out it was something simpler. if the answer is rebuild it, can i get some hints as to how i could do it myself - or is this a job that would really require me to take it back into a shop?