I have a t 350 from my car. While it is out I wanted to address a couple probs. First tranny runs and shifts great. I have no park! It is just another neutral. I've heard parking pawl? Where is it located, I've pulled the pan and all is clean no visible broken parts and shift mech moves smoothly.
2nd. I changed the rear from a 241 to a 373. I want to correct the speedo. Is there a chart to look up the gears to exchange in the drive?

 

Found this on google, I hope it helps.

It could be the "Parking Pawl control rod" is bent but I doubt it (has a spring tension system to maintain engagement). It is also unlikely (not impossible) that the hub that is attached to the tail (output) shaft is worn off. Parking Pawl could also be worn or chipped but I doubt it also (1/4 inch thick steel).
You can check the "Parking Pawl" engagement by placing a driveshaft yoke into the end of the trans and turning it while moving the shifter in and out of park. It will turn until it engages the hub and then it will lock in. If it ratchets then you can pull the pan and diagnos the problem.
This is a Turbo 350, but the idea is the same. Slot for parking pawl in lower left area of piston body. It's a pretty stout assembly.

 

Removing the pawl requires a complete teardown, but it might be the rod that actuates the pawl. If you pull the pan you can see the rod alongside the valve body and see it move when you shift the tranny into park. If it's not something to do with the rod, then you've got a major disassembly ahead.

 

Carrying a "parking brick" with you would be easier than a tear down!
I put a link with speedo gear and ratio info in the 1st gen trans section, I know you were already looking there.

 

I have a very good parking brake!! I did find the link in the 1st gen section. It is very generic. I had seen a chart somewhere before that was more camaro specific and won't require dissassembly of the speedo.
The rod all seems to move very smoothly,nothing in the pan looks to be broken etc.

 

OK Maybe some of you guys think ripping a TH350 is a long and hard job... I personally would dig it apart and think nothing of it.. they come apart easy and go back together like a dream... the biggest thing is to remember where the check ***** go when you pull off the valve body. if the Tranny shifts good then what I would do is get a gasket set and seals... replace the filter.. fix the shifter Pawl and slam that bad boy back in the Car... but then I have rebuilt 5 or 6 TH350 and 2 TH400's I would just pull the pan and look at the linkage, I would bet it got Jammed and you can free it up with a screwdriver.... Swap the filter, replace the shifter linkage shaft seal and clean the Magnet in the pan... Check the Input shaft seal, the Speedo gear Oring and output seal... now is the time to check the rear man seal on the motor is the tranny is out.

OOOPss re-read the Original... rip the tranny apart time.... lay out the parts in a line as you take them out... once you find out what happened to the parking pawl as you replace the sun gears, clutch packs and bands in the tranny make sure you spin each set to make sure they are fully seated on the gear or pack before them... if you have questions I can help with hints and tips if you think you need any words of chear from 900 miles away..

 

900 miles,I'll drop it off in the morn! LOL

 

Bring it down I will do it at work at lunch... Walk in the park... we have 20,000 Square feet of floor space I know the boss would let me use a bench for an hour or two.

 

I may be late!!LOL I should have known nothing would be easy.
SO right now I'm sweating the speedo prob. I've found lots of charts for gear changes all over the net.Not too simple. How do you count teeth on the drive gear? Straight across? I count six!! There is no 6 on the chart, chart says green is 9. I can go diag and get 8?

 

Well I figured that out!! From the end, count the beginning of each spiral.Now to find the correct driven gear.
Looks like a 25 driven with 373 and 255,60,15 tires