This is just random but chg up all of the charg’g cables, use 2-ga min.
Next replace all of the ground cables, battery to frame, to engine and one to the alternator mount. Run a new ground wire to the upper bolt on the starter; get to bare metal on all connections and seal all of the lug connections with adhesive type heat shrink.
Then replace the power cable to the starter.
While you are at it run a new ground wire from the battery to the body of the vehicle.
Now if the battery and the alternator are new then all should be good.
if there is a slow drain then start by disconnecting things that might pull juice, then check the battery to see if there is still a drain by lifting the positive cable and see if there is a spark.
From there it is trial and error.
Now there might be a better electronic way but I am old school.
4x4, 5sp, Std Cab, Stepside, E4 Red
4” Lift - Coil-Overs, 6” SkyJacker Leafs - No Blocks (Mistake)
31 Spline FX4 Rear Axle, 4.56s and OX Locker, Hurst Shifter w/Optional Stick and "Made by Grev" alignment adapter