El Camino Rear End

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lvrnespeca

Not-quite-so-new-guy
May 23, 2019
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I recently bought a 1981 El Camino with a 229 chevy motor. It had a 350c and a 271 rear end. I replaced the 229 with a stout 350 then soon had to replace the 350c with a th350. The rear end rides great. Very low RPMs while cruising and a top end that ill never hit. The Question: What would be the best rear end choice 3:24 or 3:42 I want driveability more than performance!
 

565bbchevy

Geezer
Aug 8, 2011
9,591
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If your main concern is driveability I would probably go with a 3.08 or 3.23 gear.
Also you can change rear tire height to fine tune where you want to be after gearing.
 
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ssn696

Living in the Past
Supporting Member
Jul 19, 2009
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Consider an alternative: trade the TH350 for a 700R4 and a Powertrax lunchbox locker. The lower first gear will make the 2.73 rear feel like a 3.42, and highway speeds will be lower noise and fuel consumption. Requires a lockup kit and a cross member change. The locker can be done on the axle while it's in the car.
 

jlcustomz

G-Body Guru
Nov 22, 2011
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In your case , I'd sell the th350 & get an overdrive with a lower 1st gear & a lockup.
This would be the closest thing to the best of both worlds that a modern drivetrain would provide. You'll need a shorter driveshaft & possibly different crossmember , but that's just part of the deal. Not just for fuel savings, an od trans with low ratio rear will give you much more highway comfort. My double OD t-56 /Ls1 in (.50 ratio 6th gear) with 3.73 ratio & 29" tall tires put me not getting to 2000 rpm till 92 mph.
Only other issue that could pop up would be exhaust drone, but that depends on exhaust.
 

hoffa65

Master Mechanic
Mar 11, 2019
319
416
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Atlanta GA
I have 2 200Rs Hmm.....
200r4 is a direct replacement for the TH350 same drive shaft and yoke you would have to get a cross member with frame extension for the 81, or weld in a mount for the stock 200r4 member. I'm betting you have dual exhaust now so a G-force member would be the way to go. A 3:42 gear with an OD will good all around, I think the 271 with OD and TC locked up would be lugging the motor a bit at cruze, unless you curz at 90+ lol
A fresh build (good hard parts) on a 200r4 with a Transgo shift kit would be my choice, had one in my 84 ElCo with a 3:73 LSD running a 69 327 325HP 2500 stall TC was a FUN ride.
 
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