What gears??

[Smasal]

Ok. I dont tow anything but occasionally a 12 ft trailer with two 4 wheelers on it. How do I know what gears I have? I have a 98 LT 4x4. I think I have figured out that I can just count the bolts on the rear diff and that will tell me whether its 10 or 14. But how do I know what gears I have? Is that all you guys need to know? Because my next question is I am gonna service my rear diff and I wanna give you guys the correct info to tell me what to use for oil. etc, etc

 

[SunlitComet]

Look in your glove box for a whit sticker with one of these codes on it.:

GT4 -- AXLE REAR, 3.73 RATIO
GT5 -- AXLE REAR, 4.10 RATIO
GU4 -- AXLE REAR, 3.08 RATIO
GU5 -- AXLE REAR, 3.23 RATIO
GU6 -- AXLE REAR, 3.42 RATIO
G80 -- AXLE REAR, locking

You would use gl-5 80w-90 standard gear oil.

 

[Smasal]

Looks like I have GT4. 3.73. What does that mean to a guy who doesnt do much towing? Also would 275/70/17's fit under here? Or affect the gears or be bad on anything? Sorry these are loaded, open ended questions.

 

[SunlitComet]

Quicker take off maybe but hardly a difference IMO your tire diameter will increase to 32.8 inches, your speedo will be 1 mph off. I think you will be just fine as long as your suspension is strong and not sagging. From the look of your pics I say crank your keys for an extra inch in front and call your self good

 

[Smasal]

I am gonna crank the keys as soon as I figure out where the hell they are lol. I cant believe I couldnt just lay under there and spot em. I was on my way out the door and checked real quick, dad, was in his truck waiting and in my defense the driveway was over 100 degrees). So I am gonna check tomorrow. So measure before, the front and back ground to wheel well, and then give em a couple turns? Also the only reason I am putting those tires on the truck is because these z71 wheels were already on here. Personally I miss my 16s I had on my old Tahoe. 265/75/16 would be my first choice.

 

[SunlitComet]

that is correct. start with 3-4 turns equally between left and right. Lift the front with wheels off the ground. Follow your torsion bars back into the cross member and on each one you will see a bolt in the cross member with its head pointing down. Do adjustments with no weight on front wheels and bounce the vehicle a few times(or drive) between each measurement. When you reach your sweet spot have it aligned. I would not exceed more than two in gain if you decide to go higher.