That's an 8.25" rear as stated above. Putting the larger tires on was the equivalent of putting a 2.99:1 gearset in it, and the OD top gear is the combined equivalent of adding 2.18:1 cogs out back, good grief what do you expect from that poor Slanty!! I'd toss the 3.73's in it, the new comparative final drive ratio'd be 2.52:1, if that's important to You. Personally I dislike the OD 4spd, but if I wanted to use it in Your application, I'd put 4.10's in it for a final comparative top gear of 2.77's & plenty of pulling torque to get going...and easy on the clutch.