The Link with 2 circuits splitting off.....
*1 circuit goes the the Voltage Regulator, The other feeds the Fuse Block.
The Link with a single circuit feeds the Junction Block up on the Firewall.
Those Links, Because where they're placed cause a lot of grief & fires.
There isn't a reason not to convert to Mega Fuses. Two 40 amp fuses would be perfect.
I use Fuse Holder GM part# 19116352, It's only $17. Unfortunately it comes with fuse way larger than you need so you'll need to buy 2 40 amp Mega Fuses.....Littelfuse or Eaton/Bussmann ONLY!
Use a 4 gauge wire to power the Fuse Holder, Mounting the fuse holder close to the battery is ideal because the 4 gauge wire will not be fused.
The 2 circuits that feed the Fuse Block run behind the engine, Don't be surprised if you need to cut these 2 in the middle somewhere to find "good" copper to solder to, Even if you butt splice....You need clean copper for a good connection.
Swap the 125 amp fuse to the top, Then install the 2 40 amp fuse in the bottom 2 slots.
Use the picture/diagram below to upgrade your Body/Charging circuits.