Upgrade + Downgrade two Kernel

[Papa Tana <papa.tana101@gmail.com>]

Upgrade + Downgrade Kernels

Hi All,

This is my first post as a simple Linux user.
I am using a library for programming in Linux Host which require a
specific Kernel version to work.

Some may say that it's not convenient to upgarde or downgrade my
kernel just for the sake of a library, even the word Kernel frighten
me..., but I really need this library.

Required> Debian "stretch" 9 with kernel 4.9.0-6

So, I have 2 machines:

$ uname -r
4.9.212-antix.1-amd64-smp

$lsb_release -a
No LSB modules are available.
Distributor ID: Debian
Description:    Debian GNU/Linux 10 (buster)
Release:	10
Codename:	buster

and

$uname -r
Linux version 4.9.0-4-amd64 (debian-kernel@lists.debian.org) (gcc
version 6.3.0 20170516 (Debian 6.3.0-18) ) #1 SMP Debian 4.9.51-1
(2017-09-28)

$lsb_release -a
No LSB modules are available.
Distributor ID: Debian
Description:    Debian GNU/Linux 9.12 (stretch)
Release:	9.12
Codename:	stretch

I saw a lot of commands in several forums, but as this is my first
time, and all my valuable projects are in these 2 machines, is there
any safe tutorial to :
 => Downgrade my 4.9.212-antix.1-amd64-smp to kernel 4.9.0-6
 => Upgrade my 4.9.0-4-amd64 to kernel 4.9.0-6

Thanks in advance,