transmission binding up??

It my be in the clutch not the transmission.

If it does it when you are stopped and trying to put the transmission in gear and it has a lot resistance and grinding it is probably a broken clutch brake.

If it only does it part of the time it is something else. If it is the clutch brake it will grind every time when you are trying to put it in gear from a complete stop.

Clutch brakes are a fairly easy fix. Less than $100.00 for the clutch brake and an hour or less to change.

 

like wayne says sounds like your clutch brake it will only get worse to the point you will have to turn the truck off to get it in reverse

 

As far as the welds I would jump on whoever did the work and make them fix it

 

I wouldn't. If he screwed it up once hell screw it up again. I would make the original shop pay to have it reworked by a better welder.

 

That wouldn't be soo funny if it weren't true.

 

I've delt with enough broken welds over the years. If you can't weld it right the first time, you ain't touching it again. I have 1 shop I have weld aluminum and that's Truck equipment service co in Lincoln, NE they build cornhusker 800 trailers. And I have a guy my dad used to work with weld my iron he lives about 40 miles away from me. I trust his welds with my life. He Lincoln locked an 8 3/4 dana 80 for a friend of mine. After 2 axle shafts, and about 40,000 miles not to mention all the times crawling and off roading his welds are still holding strong

Recently is the key word I'm going off of. Trucks get beat to hell going down the road, if it were welded 5-10 years ago I could see it possibly be cracked by now. Recently is a couple months or less in my mind. So no there's no excuse for those welds cracking.

 

OP,
What concerns me is that you say "when I jack knife the trailer to back in to a dock, the transmission will refuse to shift into reverse or first".

Normally, this would likely be a clutch brake problem, but if so, it would grind or refuse to engage whether the tractor/trailer was straight or angled (jack'd).
Does it grind when trying to get into reverse or first, or is your shift lever simply refusing to move into gear with never a sign of grinding?
And are you saying it shows no problem engaging when your truck is straight?

The "only when jack-knifed" issue calls for "deeper thought". The tractor/trailer angle should have no bearing, in other words.

 

If they removed a cross member, and you have broken welds, I would be checking the frame and engine/ transmission mounts thoroughly. Also check cab mounts. If the truck is an 86 model the cab mounts would be suspect.