Dex 3 is what the shop told me for trans fluid.

I did put in Trans-x, which made things better, but still slips.
;

Today, I adjusted the Bowden Cable, using the throttle rod on the IP as a reference, which took me about 5 turns in to match 'no free play' with the initial movement of the throttle rod.

Now the 300D is a totally different car, still slips, but shifting after it catches second is perfect 'luxurious'.

B2 piston?

thank you for taking the time to help me. I have been taking pictures, and I will post a album soon.