Thank you Aviat, but I am search for any current service bulletins or document that are already in the industry that perform this increase in MZFW from 106,500 lbs to 109,600 lbs for the B737-300.
There is a Boeing SB which comes as a package with a Flight Manual revision.
I am unaware of any physical config change but there may be one.
To get the SB, you pay money.
I do not know of an STC.
If you use an "illegal copy of the SB it will not have an effectivity that matches your aircraft and the FAA T.C.D.S. will not be updated to reflect the change of MZFW of your aircraft, ie. it will not match its certification data and will be officially illegal.
Sorry for the bad news.
Regards