What differential gear ratio would be best for all-around city and highway cruising for my '69 Camaro with a 396, Turbo 400, and Goodyear F70-14's. I'm currently running a 4.10 12 bolt posi and it seems to be over-reving on the highway.

RK,
I'd go with around a 3.42 or a 3.55. Your trans has a 2.52 or a 2.48 first gear, I think, so you don't want to drop all the way to like a 3.08 or you'll be awful slow from a stop. You're real close to the gearing for a wide ratio Muncie. Mine had a decent performance/highway mileage mix with 3.55's. Steve Laabs

I have a 12 bolt with 3.42's in it in my 67'.It was set-up with all new parts maybe 2000 miles ago.I am looking for 3.73-3.90,but would consider a 4.11's.wanna trade?E-mail me if interested.Where the heck is Shell Lake?Have truck,will travel.

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67 RS RAGTOP # matching,
4X4 CHEVY TRUCK

Just so you guys know, 3.42's and 4.11's use different series carriers in a 12 bolt.

Thanks Lonnie,I meant the ENTIRE rear end though.

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67 RS RAGTOP # matching,
4X4 CHEVY TRUCK

67drake, thanks but not interested in trading, will probably buy new and box up the old for some day down the road. Might look at precision gear for a new replacement.