13 speed...TOAST?? Any ideas...

Well you have done good diagnostics and a good description. I think you know the answer already, but were hoping somebody out there had a magic answer. Final question, yes, owning a truck sometimes has associated bills, but, it also has freedom and independence that you don`t find in any regular job with a boss or a supervisor. Bite the bullet, pencil out a trans rebuild, get er done, and back on the road. Good luck! And, most of all, enjoy being your own boss (within the confines of dispatched loads, etc.)

 

it is ither front diff threw shaft or rear diff ###### it coujld hopefully be a rear axel im guesing its got two rear axels also check if when you spin drive shaft dose the short shaf inbetween diffs turn if it dose not it is most likely the threw shaft have some one put transmission in gear and watch if out put shaft spins if it dose its in rear but the way you explain loosing certain gears one at a time sounds like transmission but the fact you can spin that shaft means forsure in rear it should not spin unless threw shaft in front diff broken or rear diff broken or axel broken. but once again no nosie messed up man. so what I would do is those first checks I talked about then if still not sure drain transmission and both diffs look for metal chunks on magnetic plug small shaveings are normal unless excesive amount if you do all these checks you will find witch one is your issue. I promise I change a lot of diffs and transmissions my friend

 

Wow, in all my driving days in yesterday years never had a transmission, engine, nor rear-end go out on me.

 

get some off that off road truckin in it will destroy your truck lol that's the stuff I fix plus Alberta oilfield so it attracts all the wage chasers so we get a lot of young guys 21 year olds and what not its to the point up here a driver doesn't even know how to wash. I keep trying to explain to the they are responsible if anything falls apart and hurts some one but they think because im a journey man of our company shop im the one in troublei keep telling them if dispatch asks you to go to work with something half broken they have to think they are responsible and have the rite of refusle they don't get it lol o well it sure makes for a really hard fleet to fix 15 trucks 30 trailers one mechanic lol I should be at work now lol

 

Sounds like the diff needs some work, but think you lost your clutch adjustment. Maybe your clutch is at the end of its life or was adjusted wrong - won't hold adjustment. If the free play is minimal you'll lose higher gears first.

Did you check free play, push the clutch pedal with your hand, does it move 1-2" down before any resistance is felt?

 

Seems like more than quaincidence that you had "adjusted" clutch and now trouble , why did the clutch need adjusting ' how much adjusting ect? A clutch that was out would also not hold in high gears first then eventually at all , let us know what u end up replacing , thanks.

 

Regardless of all transmission problems you should never be Abel to turn drive shaft wich I can assure you means there is problems in rear diff front diff or front diff threw shaft or axel broken.

 

Ibet it's front diff threw shaft

 

I've also seen yoke in front diff over heat because the oil was not getting that high and the yoke and splines melted rite off of course that happened because there was such low oil in diff