1993 850 Heater core replacement

[Mister_Blue_Sky]

Hello All,
The car is a 1993 (I think) Auto Sedan.

My heater core has failed me, resulting in my poor flooring being soaked with 8+ litres of coolant.

Having looked at a few videos of how to replace the heater core, I took apart the coverings around it, only to discover that it has a silver box with wiring attached to it via a bracket. I think I can remove it without too much difficulty, but I just wanted to know

a) what it is
b) should I be wary of anything when removing it, and
c) as a bonus, what is the black modem-esq box?

My apologies for my first-time-post / Volvo-noob, I haven't had much experience taking these beautiful beasts apart.

Mysterious Silver Box

Mysterious Black Box

[abscate]

Silver thing looks like an amplifier , the black box I would guess a mobile phone install from the Jurassic era

[Clemens]

Yes, it is the amp uo to 96. Very good unit in my opinion. Re move it, then proceed with the heater core replacement. Don't foeget to dry the wet spots really good.

[precopster]

You have black steel pipes to the heater core. They usually corrode badly at the seal end and cause leaks. If you're close by to a Volvo wrecker it would pay to get the later aluminium ones from an 1996/1997 850 or a 1998-2000 S70 or V70

[polskamafia mjl]

As mentioned that's an amp. Removal isn't difficult but I spent quite some time trying to maneuver it out of there. It's just a lot of twisting and turning. Reattaching the wiring connectors is also annoying.