Fresh C6 Rebuild Shift Issue

[divemaster5734]

Broke my cherry doing this c6 rebuild.
Did a stage 1 shift and new TC.
Replaced both internal and external filters with exact replacements.
Used Merc V.
All the air checks performed, all the tolerances were perfect, ended up with .030 end play.
It shifts through all gears nicely, except when first starting.
It takes a minute to engage.
Once driven a couple miles it works flawlessly.
On flat ground in park when hot it's at the top of the hatch marks.
Only problem is I don't trust the dipstick.
It's obviously the original, having been a U Haul rental box truck for 170k miles and going through hundreds of drivers, it's seen better days.
The stop at the loop handle doesn't stop anymore, there's a flat plate I believe may have held a stopper at one time, but that stopper is gone and the flat plate has around a 2" travel.
Looked around and couldn't find an exact replacement, only "universal" ones that need to be adjusted, assuming it already has the correct level.
Not sure what to do, obviously don't want to overfill, but that cold takeoff slipping is only destroying all the new plates.

 

[franklin2]

In my experience, if the c6 is fully drained, it takes about 13 quarts to get it back where it needs to be. That is when I would drain the torque convertor drain and pull the pan. I remember it's just over a full case of 12 quarts.

 

[divemaster5734]

Unfortunately that ship has sailed.
I messed up initially and didn't have the park pawl set correctly, which wasn't discovered until installed, so I drained the fluid, pulled the transmission out and fixed it on the bench.
Put another 3 gallons of new ATF on reinstall.
Then stuck a vacuum bleeder down the dipstick hole and sucked out about 1 1/2 quarts when the stick showed high.
Am not sure about the exact amount that was extracted as the bleeder reservoir doesn't have level markings and there was brake fluid from brakes, more brake fluid from a new clutch master, line and slave, and more atf from a ps pump replacement.
I have to grease the new U joints today, but think I'll add a 1/2 quart and see if there's any improvement.
I know that's a slippery slope, but already have used 6 1/2 gallons of ATF, and hoping to avoid crawling under that low E350 and pulling the left exhaust to get to the inspection cover.
Think I'm going to clean out that reservoir and mark out levels one qt at a time, it'll definitely help in the future.
I do recall there was a much better response on the first check out drive than the second, and I didn't see any indications of fluid blow out when pulling it to fix the pawl.
Even better, after getting it on the bench again I realized the rod could have easily been set with it still attached.
Some lessons are freaking hard learned...

 

[XOLATEM]

except when first starting.
It takes a minute to engage.

Does it do the same thing in forward and reverse...

Or...does it do a delayed engagement when cold in only forward...or reverse...?

Other than what you are doing...on the fluid level check...that would be the next thing to iron out...

Are you certain that when you select a gear...that the linkage is sitting squarely in the detent...and not partway towards another gear..?

Just tryin' to help...

Oh, yeah...just remembered something...

Got a test (diagnostic test) for ya...

When the thing is cold...and/or has sat overnight...or a couple of days...

without starting the engine...pull the stick and see where the fluid level is...and then wipe it off and stick it again and see where the level is...and...once more...wipe it off (the stick) and stick it again and pull it out and observe...

Then...start it up and let it run for a while and then check the fluid like you normally would and then post your observations...

with a little help...you'll figure this thing out...

 

[divemaster5734]

No worries, it usually is something stupid.
Yes, either way it's the same until I drive a mile or two.
The detent is operating perfectly.
Once it's operating it works great.
If the detent was off I don't think it would correct itself.

 

[divemaster5734]

Added 1/2 quart and that did the trick.
Got a feeling it might still be a little low, but going to call around and see if a salvage has a dip stick available.