Modding stock vehicles after new .8 Powertrain updates

Anyone found out where to change things like the axle ratios on the D Series now after the new powertrain layout has rolled out? I can make plenty of power but 60 MPH in first gear is just a bit unrealistic. Any help appreciated! I searched but all I've found has been for pre .8 powertrain info.

 

As far as modding axle gear ratios, it's still the same as before Powertrain update.

Example, to add a custom rear differential to the pickup/roamer:

Pick a differential from the vehicles/common/pickup/pickup_suspension_R.jbeam - then make a new jbeam file for your mod that matches, but with your modifications

Code:

{
"pickup_differential_R_custom": {
    "information":{
        "authors":"BeamNG",
        "name":"My Custom 5.17 Rear Differential",
        "value":350,
    },
    "slotType" : "pickup_differential_R",
    "slots": [
        ["type", "default", "description"]
        ["pickup_driveshaft_R","pickup_driveshaft_R","Rear Driveshaft"],
    ],
    "powertrain" : [
        ["type", "name", "inputName", "inputIndex"]
        //rear diff
        ["differential", "differential_R", "driveshaft_R", 1, {"diffType":"open", "gearRatio":5.17, "friction":5}]
    ],
},
}

The gear ratio is there in the "powertrain" entry. Apparently I can't make code bold