Transmission Stuck in First Gear

OK guru's I need your help. I have a 1974 Loadstar 1700 345CI 5 Speed Manual transmission with a two speed rear end.

Here is the problem. While plowing snow today I began to notice that the transmission was not shifting so smoothly as I made various passes plowing snow. This required a lot of backing up in reverse and then going forward over and over. I thought perhaps it was just the cold weather.

Well on my last push I could not shift back into reverse or any gear for that matter. Its stuck in first. When I engage the clutch the engine will rev up fine and not cause the truck to move so I dont think its a clutch issue. The problem is I cant budge the shifting rod and change gears.

Any ideas or solutions. Thanks for taking the time to review my problem and offer suggestions.

Craig

Could be in the shift tower, or it could be inside the transmission. A broken shiftrail interlock can jam the shiftrails. A bent shift fork or cracked dog-clutch could also cause it to stick.
No way to tell from this end of a keyboard. I would start by pulling the shift rod out of the tower and see if the gates are lined up on the rails that should be in neutral, while the 1st gear is engaged, if they are slightly out of line, line them up and see if you can then move the 1st gear rod to neutral. If that doesn't help, than the top cover has to come off for a better look.

I am all in favour of taking the top off for a better look.

Thanks for your input. I will update on where the investigation leads me. I'm going to let it warm up for a few days before I get into this because I have to work on it in my shed and its 3 degrees out right now. Craig

Anything lighter-duty that would be a clutch hydraulic or linkage problem 99% of that time.
I'm watching the top come off with interest. How big are these shift towers?

Sorry I have not got back on sooner. As it happens my nephew, who is a heavy equipment mechanic believe it is a worn our tower unit but will be visiting this weekend and volunteered to help look into this, which I am totally grateful for.

More news to come next week, I only hope it warms up. Otherwise I will be tarping the truck and putting my torpedo heater at the front of the truck and warming up the environment.

That's what you get for living up "North Idaho!" It was 5 at 5:00 this morning when I got back from a run down from Spokane. Make sure you do not Gas yourself out when you cover up! But I thought that the Top was going to come off, so you want it to be warm!

Yes will have the doors wide open while working on it . If need be I will revert to the electric heaters. Like to get it done this weekend thought as it looks like will be in the minus degrees come Tuesday.

Ok I have pulled the top plate off and discovered one of the ears broke off on the rear shifting fork. I found the piece at the bottom of the transmission. Can this ear be welded back on with some success because I would not know where to get a replace fork.

Also would this have caused the shift lever to jam.

The gears all appear to be OK and clutches and synchronizers move freely and spring return them.

I would appreciate your opinions on the welding aspect of this and if that is not a good idea where I might go for a part.

I am pretty sure this transmission is a T496. At least that is what is says on the truck script, which I have when the truck was build in 1976.

You thoughts? Craig

Yes, if the fork is broke, the dog will bind. I think you found the problem.