eb3 to eb2 conversion

[is_gc_worth_it]

I have 140 approved under eb3 and 485 pending with priority dates of April 2003. If I file a new 140 under eb2 from the same company.
1)can I still keep my old priority date or would I be assigned a new priority date.
2) is my old 140 invalidated , when I file new 140.

thanks very much.