Yaesu FT-847 Modification Manual page 21

Assuming you did also small ground connection to near filter shield to make
filter module straight and to ground it - this is the end of mod. So we ended up with
filter board looking like below.
You can mount the PCB in the chassis, connect all remaining cables and
connectors and be happy with your FT847.
Please be careful when You cover the upper shield with speaker. Sometimes
You will need to turn the speaker around to move audio soldering points to another
position avoid short circuit with filter board.
There's not much place to do anything, and we just added two small but PCB. If
the speaker will be to close with filter PCB you can bent the RX PCB toward front of
the radio. It will increase the space between the speaker and filter PCB and it will fit
OK.
Note : Although I am sure that this mod is repeatable, and anyone can get similar
parameters, final result depends on fact if there was any attempt to modify RX gain.
It will be good to get into service menu of the RIG and check RX-CHAIN parameter
and correct the gain if needed. Standard Hex note for RX-CHAIN parameter is
Something like 3E for model 9I and 4E for earlier 8G. The lower Hex, the lower gain.
Disclaimer: This article is written for information purposes only.
Although all described mods were carefully tested myself on my own radio, back and
forth in the period of last year of my activity on 4m, I shall not be judged responsible
for any damages/failures of your transceiver, if something will go wrong.
All mod's you just doing on your own responsibility.
If You are not sure You can do it yourself, better ask a friend. Or if You want to
push more life in your 847 and you don't know how, write me. We are living on the
same planet 
Sincerely thanks for Marc PA1O, for his super job, and Hellar ES1II with Arvo
ES1CW for many hints about 847 mods and Jacek SP3LYU for loan me his FT847
to do .
Best DX DX, 73
Greg SP3RNZ Oct.2013