Just installed a C6 that the NSS seems to be about a 1/2 thread off from correct setting.
I pulled the switch, and marked electronic Park, Reverse, and Neutral with a sharpie to make setting easier.
With the column linkage completely loosened I can't get the transmission setting to line up correctly.
The NSS mounts with two bolts on elongated slots to allow for adjustment, but as you can see from the picture, that's a 1/2 mount hole from where the switch lines up internally.

You can see the threads for the mount through the slot at the bottom.
The mark on the switch is reverse, but with it in reverse the switch won't mount.
The shift lever goes cleanly through all the gears, and the kick down linkage lines up and returns the throttle linkage.
I was very careful to set the shift fork inside the plunger on the valve body with the downshift between the **** and other plunger.
I haven't started the truck yet, so no ATF has been circulated through the C6, which means obviously that the valves are not yet operating.
I was going to put the rear axle on jack stands to fire it up and get the transmission operational, but that wouldn't cure my problem.
I'm ready to cut the ends off on the switch so it mounts, but decided to make this post in hopes someone may already know exactly what I did wrong.
Looking at the picture again I do see the collected dirt.
I don't think that's enough co cause the issue, but I'll drag the air gun down there tomorrow and blow it out anyway.

 

what year truck? ?there is adjustment on the shifter cable, or linkage if it has linkage

 

It's a 1991 E350 stripped long chassis with a 20' U Haul box.
It has linkage.
I thought it might be in the linkage also, so I disconnected it completely.
The problem is the switch won't time with the transmission's internal shift.
I did have it stripped down to the case, which includes the internal shifting arms.
On reassembly I had to consult some of the tear down pictures because it was possible to install the shaft runs from the exterior linkage through the inside, past the drive and foreword drums, and operates both the shift arms, as that main shaft could be installed in four positions.
There was only one position that could have possibly worked perfectly with all the internals, all the other possibilities were 25°, 50°, or 75° off.
I didn't see how it could have been possible to be off by 1° or 2°.

Took this just before starting assembly.

Here's a pic of the two shift actuators before setting the valve body.

The 90 hook is the downshift and the wide one is the gear shift to the valve body.


The valve body went on perfectly, the shifter went through all the gears, P R N D 2 1 perfectly.
I'm split between draining the oil pan and pulling the valve body, but replacing it while laying under the truck will be challenging due to the different perspectives needed to set the two levers, not to mention the drums that will prevent getting a wrench on the valve shifter nut.
I'm thinking the best option would be to leave the NSS off, hook up the control linkage, get it started and ATF circulated, and see what happens when put into gear with the rear axle on jacks.
I don't have the equipment to recover the 12 quarts of fresh ATF without contaminating it, so would have to replace it, along with the pan gasket.
Thinking if I'm going to waste that $70 and extra day of fun and games then might as well see if it will work.

 

i like your game plan leave the NSS in either park or neutral position and wire it up out of the way in a safe place. once everything is in known working order you can come back to the NSS at a later date.... it has been at least 35 years since i had C-6 apart, so i am no help with that.
is it possible the NSS is internally off/bad?

 

I was wondering the same thing.
It may be possible to get up to 1/32" or even 1/16" play out of the shift shaft, which may be just enough to put the NSS switch in range, but that said, it's obvious the switch itself doesn't throw at the factory Neutral mark.
Referring to the close-up of the NSS, the actual N switch position is offset slightly from the indicated spot on the switch body.
Thinking about it I just realized I know where there's an abandoned E4OD that may have a NSS that could work, since there's really only three positions that matter, which are the same on both transmissions.
35 years, I know, the mandatory 20 year spare parts run required by the NTSB after an assembly has been obsoleted ran out for the E4OD, which was the only tranny that shared any parts with the C6.
Had to call several of the online specialty parts stores before finding a guy in California that was happy to send his entire collection of related snap rings for the cost of postage.
He was glad he didn't have to throw them out, except I now have several rear planetary output shaft snap rings that I can't throw out either.

I appreciate the conversation, it helps to kick ideas around.

 

is that the nss that came off the trans?
a new one is still only around $55 on the internet.

 

[QUOTE=tjc transport;21343707]is that the nss that came off the trans?
It is.
There is a lot of play for sure.
I'm also doing a resto-mod on a 1989 C350 - base is a Lariat XLT 7.3 with a Centurion 4 Door Bronco conversion.
Swapped out the E4OD to a ZF542 5 speed stick, updated the 088 turbo with a Garrett 65mm fan, stage 1 injectors and a 110cc pump.
Resealed and painted the engine. Am swapping out the axles to '03 SD, D60 front/ Sterling rear 10.5" with all disk brakes right now, but took a break to get the box truck running, as I closed down a construction company in 2021 and retired, now am downsizing in preparation to sell my home and leave this state.

Have some spare parts from the C350 project, including the NSS. It's over at a friends place where I have it in a covered and secure area, I'll head over tomorrow.
Went to check the oil today on the E350 and got a dipstick surprise

Broken dipstick
Then went to harness the GP relay wires to install the engine cowl.

Hate working on this old stuff.
It's going to be so nice to see that van drive away for the last time.

 

Just a quick update, I wound up pulling it out and realized I buggered up the valve body placement.
After correct setting the range of motion was not only perfect, the engineering behind the design was almost idiot proof, but I showed them...lol
I did spend a couple moments in enlightened appreciation for top level engineers.
Just trying to determine all the different calculations, processes, and competing forces at play to just switch gears at the drivers seat and have the valve body slide a fraction of an inch to redirect hydraulic fluid almost gave me an aneurism.
I appreciate your comments.
Thanks