[Jesse B.]

I'd re-gear for the reasons above, and because 3.73 is too low. A 4L65 has an OD of 0.70. With 33" tires and 3.73 gears, you will be turning 1861 RPM at 70 MPH.

I think 1861 is too low for 70 MPH. You'll be too far below your torque curve and will be lugging the engine. In addition, when driving around town at speeds above about 40 mph, the trans will shift into OD, so you will be lugging even worse at lower speeds.

With 4.11 you'll be turning 2051 RPM at 70 MPH. I have a 4L60 in mine with 4.11 gears, a RamJet 350, and 33s and it cruises at 70. I would never go down to 3.73.

Lastly, if you are going to open up the case, I recommend installing an LSD in the rear.