All are half ton TVs vs the OPs...and...if the OP's has the F60 option (look at the RPO code label in the glovebox door)...he has a 1 ton Suburban...via the 1 ton front torsion springs
That F60 snow plow prep otion also begets the 1 ton rear shoe/drum brakes...why parts counter folks always ask what shoe width. Regular 3/4 ton has 2.5in wide and the 1 ton has 3.5 in wide shoes...ops...he has the rear disc setup...don't know if it has the 1 ton rear brakes
Or if the number of wheel lugs makes more sense...half tons typically has6 lugs and 3/4 ton and 1 ton has 8. The fake half ton has 7 lugs & LT tires
Changing diff gearset to 4.88's is about $1k per in my area. The 0.5 or 0.7 OD from Gearvendors is about $4k. A higher 8th gear (double OD) than the stock 4th
That allows the oversized tires the OP has to stay and mostly still be able to smoke them...even with torque management
Then have a higher GCWR, but 4.88 is off their charts...so my guess...since their charts stop at 4.1...which is higher than 3.73's