I have a 1973 Blazer with a LS swap and 4L60E tranny, 4" lift with 33" tires. I changed the gear ratio to 4.56. I think for my set-up, the 4.56 is perfect. If I was running bigger tires, I would definitely go with the 4.88. I am in Capitola. I had Rearend Specialty in Santa Clara change the gear...