Valve body questions

Hi,
I recently had a transmission overhaul since the 3rd gear is slipping(replaced linings and gaskets) the car is a W210 with a 4cylinder 2.3
but after the repair, it was still slipping in 3rd gear!! I borrowed a valve body from a W201 190E and now, the slip is gone. The shifting is quite fast in "E" mode but it pulls perfectly without any shift shock in 2nd gear. It really runs great.

Question:
1) Is this valve body swap OK? since the part came from a different benz with a different transmission? The shop also showed me a W126 valve body which they claim is identical to the W201. It is just a body stamp?

2) Is this valve body repairable? or better just get a used one? since a new valve body cost a fortune.

3) Can this slip be remedied by adjusting the modulator valve?

Thanks for any help..