Here's the cover for the shift valves and springs hopefully this will help you reference where they are.
Here is the spring that deals with the 2-3 shift.
slide it on out
For more referencing.
I aligned the spring on the shift valve and bottomed the stem on the work bench and found that the spring never fully compressed. I also tried to find a sae washer that would work, but all were to thick and would impede on the overall valve travel.
I measured the spring before I decided to stretch it. From the other link I found the spring looked to be about 1/8" longer than the one it replaced. I figured what the hell lets start there.
I stretched the spring out the best I could, and stopped at 1/8". I assembled everything back together and went for a test drive.
Part throttle shifts are at the same rpm. I locked my hubs in so I wouldn't have to worry about wheel spin in valet mode. Still lights the tires off till the 2-3 shift if I don't.
My 1-2 shift was at 2900rpm. I could actually barely feel the truck defuel at that rpm. Then came the moment of truth, the 2-3 shift went to about 2750rpm.
Not all that bad since it was not surging the charger. But not at a 3200 rpm defueled point ether. I would actually like to get some more rpm out of it and then dial it back with the tv cable. But it is a improvement from where I was.
Hope this helps some of you in the same boat as me. Don't be afraid of your valvebody!!!