1978 Manual Tranny Problems

[Jimmy3-speed]

 Manual transmissions options

I have a 1978 GMC (Chevy) 1/2-ton shortbed 250 with a 3-speed manual.  I shelled the tranny and found a used one that was supposedly in the original vehicle a short time before being swapped for an automatic.  The transmission shifts and works good but makes a heck of  noise in 1st and 2nd gear.  I'm guessing the bearings are rusty.  Is there any chance things will quieten down or are the bearings doomed to seize up?  The transmission was drained and filled with fresh 80/90.

[zieg85]

If the bearings are pitted, it will only get worse.

[Irish_Alley]

what type of noise. the clutch and pilot bearing should be changed when you swap it out due to the fact you don't know what it was doing before and how long it was running.

[Jimmy3-speed]

A new clutch kit was put in at the same time, Irish.  The mechanic that did it
said the transmission noise was due to rust and that it would quite after being driven awhile.  He said the bearings were good, but I don't know how the determined that.  The sound is about what you would expect a rough bearing to sound like.  I also get the sound when idling in neutral with the clutch out so that sounds like a front output bearing.  What I can't understand is why it's quiet as a mouse while going down the road in high gear.

[Irish_Alley]

A new clutch kit was put in at the same time, Irish.  The mechanic that did it
said the transmission noise was due to rust and that it would quite after being driven awhile.  He said the bearings were good, but I don't know how the determined that.  The sound is about what you would expect a rough bearing to sound like.  I also get the sound when idling in neutral with the clutch out so that sounds like a front output bearing.  What I can't understand is why it's quiet as a mouse while going down the road in high gear.

the little details come out lol

[1980c10]

This also sounds like it could be a worn throw out bearing. Does the sound go away if you lightly rest your foot on the gas pedal while idling? This will tell you which bearing it is although I can't remember which is which at the moment. Maybe someone here knows.

[Irish_Alley]

THAT'S WHAT I WAS THINKING BUT HE SAID THE MECHANIC PUT THE NEW KIT IN. THE BEARING IS INCLUDED IN THE KIT

[Jimmy3-speed]

Several people have told me my transmission noise is due to a rough imput shaft bearing.  Could this be changed by one not so mechanically gifted?  I've changed clutches before so I would know how to remove and reinstall the tranny.
When I look at a schematic of the transmission; though , it kind of reminds me of a fishing reel.  I've taken several of those apart in my day, and have yet to ever get one back together