Go ahead and waste your time and money rebuilding the trans. The rebuild can last exactly 30 seconds slipping before it burns a clutch pack up from slipping if you don't catch the problem. New parts don't mean good parts so if you introduce a second problem it gets more fun.
i don't "fix" stuff on suggestions or suspicion... i dont fire the parts cannon, unless its common, cheap, fast and contrary to that proving the failed part is a PITA.
what i do is diagnose the faulty part and then go from there, hence why im so allergic to trans specialists telling me to do a rebuild. if its an outside of trans case issue, the new one would be a DOA too.
and if i need to rebuild anyway, driving a while in 3rd wont do too much MORE damage....
The Overrun clutch for manual 3rd is a weak point. Doesn't take much to burn it up.
what do i need to avoid to not burn up the 3rd overrun clutch?
You are taking the grades too fast and/or too heavy if you burn the brakes up.
no my friend, i took a 21k lbs motorhome that was built on a 15k or so Chevy chassis, that has factory brakes that are renown for dragging, out on mountain grades with at least 25 year old dot 3 in the system and a non working tag axle brake that was supposed to take up 8k of those 21k.
missing over 30% of your capacity, old fluids and dragging calipers is a real bad combination.
last time i came down pike peak, the ranger checking brakes mid way, went to get an other thermometer because she thought hers was broken... im a German, we know how to drive.
today i did Vancouver Whistler Merritt Vancouver. a 740km / 450 miles round trip, mostly though steep mountain grades, look it up, you probably can count on two hands my brake application. and my average fuel consumption over the whole trip was about 30% lower than the 5000km average of the car i had. 11,7 ves 9.1 L/100km, but i was mostly the fastest on the road, a road ive never driven before.
i do know how to drive, like most Germans do, we need to, with no speed limits on the Autobahn, if you don't you end up as road kill.
but no matter how less you touch the pedal, if the dragging calipers make the discs starting to crack, you wont need much to have wasted brakes. and the other conditions didn't make it better, now did they.
hence why i did a full rebuild on them earlier this year. before we started into the next season. both masters, hoses, calipers, pads and drum assembly. on the front new bearings and discs and abs sensors too, on the drive i haven't had the opportunity jet to replace the disc's, no clean environment to open up the axle.
ever since no break problems, even on the steep roads around Telluride and in the Sierra Nevada and Yosemite and Sequoia NP...
i also now know how to use the 454 as engine brake, wired up a kill switch to the injectors, so that i actually can have it pump lots of air at wide open throttle, compared to idle injector cut off down hill, where your mostly having vacuum as engine brake at 140mbar of manifold pressure. and sucking against 0.85 bar is way less energy consuming than compressing to 10.5 bar...
and since i can reset check engine light with my scanner at a buttons touch, i dont care to much that this triggers a fault...
unfortunately the funny contraption of P30 parking brake wont allow me to cut off ignition and then WOT the engine for braking. that would make the auto parking brake apply, ive burned it up once, learned my lesson.