I want to change the rear differential gear from a stock 3.08 to 3.73 in preparation for adding a tremic TKO 600 5 speed with a .64 5th gear.  A local shop is telling me the correct gear would be 3.70 and not 3.73.  I know this is not much of a difference but isn't there only one correct answer to this question. If so which is correct.  Thanks for the help.

The factory gear ratio would be 3.73...aftermarket gear sets may be a slightly different ratio. Either will be pretty much the same, and either will fit the housing. SO...if all that is available for your year/housing is the 3.70, then that's what you can use with no problems.

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I'm going to install a 3.73 differential this winter - most everyone I talk to says 3.73 is too much...... Let us know how you like it.

Phill's Vette2009-09-05 12:36:44

My differential recieved a factory replacement set of 3.70s. I think that ratio was standard for a while. LukesVette2009-09-05 14:13:34

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Joels right 3.70's are 3.700I812 and 3.73's are 3.7300u812, rounded off,so whats the diff?

Paul(LukesVette) caught my typo...the 3.70 was factory...
Still, there will be no discernible difference in the two gear sets, except possibly on a loong road trip. The 3.70 might give ya a wee bit better mileage, but prolly not enough to make a big deal. You also won't be able to feel any difference in take-off  grunt between the two ratios.


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Joel Adams
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Jest makin sher we maintains accerit infermashun thar pardner

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[QUOTE=Phill's Vette] I'm going to install a 3.73 differential this winter - most everyone I talk to says 3.73 is too much...... Let us know how you like it.

[/QUOTE] On an '82 the 3.73 may be too much. The 700R4 trans has a 3.08:1 first gear (very low) and with a 3.73:1 rear you will be thru 1st gear in about a 1/2 second. I have 3.55:1 rear gears and they are fine, still goes thru 1st in a heartbeat. This only applies to the '82.

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Dave's '82

   

yeah, that's what I'm hearing. If I don't like it, I will rebuild the original differential with 3:55 and sell the 3:73.
Thanks Dave!

[QUOTE=Phill's Vette] I'm going to install a 3.73 differential this winter - most everyone I talk to says 3.73 is too much...... Let us know how you like it.

[/QUOTE]

I have 3.08 375 hp 4 speed car would a 3.70 be better then a 3.08? 

most definatelly, it would be alot quicker, of coarse your gas milage would go down the drain and the motor would work a little more at cruise and top end world drop a little, a happy medium would be 355's which I have in the LT-1 and I get about 10-12 MPG average. anips2009-09-06 18:02:20

Just to clear up. 3:70 is the correct ratio for the fatory corvette rearend housing. 3:73 gears fit in the 10 bolt and 12 bolt chevy rearends but will not fit in the factory corvette rearend housing. I think you'll like the 3:55 better as well.