Need Some Input

[69 longhorn]

I beleive you can also get 4.10, & 4.56 gears to fit a 3 series carrier.....if you already have a 3 series posi, that would be the cheapest route to go. you might consider tire height before swapping gears, the 4.10's really "spin' the eng on the hyway! I pulled the 4.10s out of my 69, & went back to the stock 3.40 gears(75 12 bolt). on a 28" tall tire, 400 turbo, the 4.10s reved my 383 right @ 4000 to keep pace with the 18 wheelers on the interstate(they run 78mph through Illinois). IMO, 3.73 is a better all around gear, & still has some good kick on takeoff. I run a 29" tire with the 3.40 gears, & tach 3000 rpms @ 73 mph. it lost a little kick on takeoff, but the 383 pulls hard from 2500-5500. it runs easy on the open hyway tho(5000 will put the speedo needle straight down). the 4.10s, & the Richmond trans are under the bench for another project.......69L