904 Transmission Stopped Going Into Gear

Hello 904 experts,

I am having a frustrating problem with my trans.

The car is a 1972 Duster with a 225 slant 6 and 904 3 speed auto trans. This is my first MOPAR project. You can follow along my progress so far on this thread: 72 Duster Resurrection


This is what happened

I got everything together and drove around the block for the first time a few days ago. Everything was fine, shifting into gear ok-ish and then it slowed to a stop on the road with the rpm still high and in drive. I pulled over and consulted the internet which told me the kickdown linkage might have come off.

I check under the hood and sure enough, the kickdown rod had come loose from the carb linkage. The spring that holds it in place is missing. I reconnected it, then carefully shifted back into drive and the car moved. This happened once more on my 5 min drive back home. This was all at sub 30mph speeds.

This is what I have done

Once home, i put a spring on the kickdown linkage and it looks like it holds itself on the throttle for now.

But the car will only go into gear.....sometimes. I can get reverse if I shift to R and rev up a bit then let the car fall back to idle. That seems to get it to shift.

I can only get drive rarely by fiddling with the shifter and throttle. And even then it feels....slippy, not good enough to go on the road. The shifter travels freely across all gears and feels like it goes into a good detent for each gear.

I did a lot of reading and decided to check fluid level first. After warm up and idling in neutral, the fluid showed low on the dipstick. I added fluid until now it shows a bit over the full line while hot and idling in neutral.

But the car will only go into gear.....sometimes. I can get reverse if I shift to R and rev up a bit then let the car fall back to idle. That sometimes seems to get it to shift.

I can only get drive sometimes by fiddling with the shifter and throttle. And even then it feels....slippy. The shifter travels freely across all gears and feels like it goes into a good detent for each gear.

What do you guys think is next?

Kickdown linkage adjustment?
Shift linkage adjustment?
Drop trans pan and have a look?

Thanks