Want to know if the hyd pump of the cat 350 L has same structure as the 330B. Also, id it can be used on other machine like 345B or any other.
I assume that you mean the main hydraulic (implement) pump. Without knowing what Serial Number prefix of 330B (there are 14 of them) it's difficult to say if the pump will fit or not, but my initial thought is no. As regards the same pump fitting a 345B, the answer is that it's also unlikely.
Do you have any schematic showing the hydraulic pump of the 350L disassembled
Send me a PM with the exact Serial Number of your machine and your e-mail address. I'm sure I can find something to send to you.