I have a 87 GMC700 dump truck with a 5 speed trans. with a 366 engine that i use around the farm.The trans.has been very noisy ever since i have owned it.It growls real bad in every gear except 5th it is quiet as a mouse when it is in that gear.It shifts good and does not jump out of gear.It has the parking brake assembley on the back.When it is idling in neutral and you apply parking brake the growling gets worse.It leaks a small amount of gear oil out of the back and i can grab the yoke where driveshaft goes and feel slack on the out put shaft by moving it up and down.I have the trans. out now and i have to make a decision.What kind of problems do you think are inside the trans.?Would you try to get it rebuilt or take a chance on a used one?I found one for $200 that's supposed to be good but the yoke is a different size and it does not have a PTO so i would have to use my PTO assembly.I only use this truck a couple 100 miles a year and the only reason i pulled the trans. is because clutch needed replacing.
It might be a bearing or something else internal?? I have seen them tranny's around here from 150 to 600 bucks. What's a real shame is when scrap prices were high everyone and their dog were scrapping on old farms around here and I've seen countless old trucks like these going to the scrapyards with plenty of good parts. Good luck when you get it figured out let us know what you came up with.
That sounds like trouble on the "mainshaft".Could be a loose or bad bearing on it.While its out of the truck you might pull the top off the tranny & shake around on the mainshaft & counter shaft.
If 5th gear is a "direct" gear and not "OD", then the problem is bearing failure where input shaft meets output shaft. In all under and OD gears, the two shafts turn at different ratios and the bearing supporting the two shafts rotates and carries the load, which creates noise in a failed bearing. When in direct gear, the input and output shafts are meshed together and the bearing isn't turning, no noise from failed bearing. If 5th gear is OD, then what I've said does not apply.
69zFarmer: Im sure there is aplace that has some used, and some rebuilt, and maybe even a new one! If you get a gurantee that the used is good, and if it's not get a replacement, that would be the way to go! I had a 435 New Process for $200.00 just to get rid of it! No one hit! When scrap was up, I too her into the scrap yard, and got $175.00 for her! Whe you find what you need at a price that you can afford, is truely a blessing!