Unfortunately they are not identical, 3-28 uses a type 4005 , 3-32 uses a type 4003 Digital Surround Sound module
The main chassis of both TV's is completely different!
3-28 is based on BeoVision 1
3-32 is more or less an Avant wo VCR/DVD built in
Maybe the DSS-PCB is equal but the rest of the hardware
(length of cables / mounting frame / ...) will be different.
There is also a very tricky SMD soldering issue on some BV3-32 to do before mounting the DSS-Module.
I STRONGLY recommend to contact local B&O service / a qualified B&O service technician to check possibility
and costs of swaping the DSS-Module to the 3-32 (serial# of both units will always be helpful to him/her)