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what rear end would i have in my car?

 
Old 02-05-2019, 08:30 PM
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bud40oz
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Default what rear end would i have in my car?

it is a 91 convertible ZF 6 speed. all i have is the rpo code sheet i was given when i bought it. it says.... G87= gear, ring 8.50 inch 8.50 inch diameter R/GR (G87) then the next line on the sheet says GM3= axle,rear 3.45 ratio 3.45R(GM3)
is that the standard ration or was it ordered with the 3.45 gears, i have read a lot of people saying they have 3.07 gears in that year.
the transmission rpo is ML9 and then next line it has MN6 which i already tracked down to the zf, and i have read those are only good for around 450 pound of torque or so, is that true?

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Old 02-05-2019, 08:50 PM
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DykstraMotorsports
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Originally Posted by bud40oz View Post
it is a 91 convertible ZF 6 speed. all i have is the rpo code sheet i was given when i bought it. it says.... G87= gear, ring 8.50 inch 8.50 inch diameter R/GR (G87) then the next line on the sheet says GM3= axle,rear 3.45 ratio 3.45R(GM3)
is that the standard ration or was it ordered with the 3.45 gears, i have read a lot of people saying they have 3.07 gears in that year.
the transmission rpo is ML9 and then next line it has MN6 which i already tracked down to the zf, and i have read those are only good for around 450 pound of torque or so, is that true?
Dana 44
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Old 02-05-2019, 09:09 PM
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rklessdriver
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You have a D44 with 3.45 ratio.

The ZF6 is an unbelievably strong and smooth shifting transmission for a production piece. I ran in the 10s with a 500RWHP 400+RWTQ 383 in my 92 without a problem ever. Another member here run low 9s on his ZF6 with a 450 inch SBC on nitrous..... 450tq is a cakewalk for the ZF. Many members here are running lots of power without a problem. The only reason GM didn't use it in other platforms is the size and fact that the Borg Warner T56 could be mfgrd cheaper in Mexico vs the German ZF6.
Will

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Old 02-05-2019, 10:26 PM
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bud40oz
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that's great news from both of you thank you both, would you say both of those parts were a special order option then?
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Old 02-05-2019, 11:54 PM
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The ZF transmission was installed if the car was ordered with a manual transmission instead of an automatic transmission. The manual transmission dictates the Dana 44 with 3:45 gears would be installed rather than the smaller Dana 36 that was included with automatic transmissions. So if you consider checking manual on the order form as special order, then yes this is a special order that had no addional cost.
You can download a free app that is called “Corvette DNA” and it will show options with cost for any year Corvette. Nice quick tool to give you some idea of values for each year and their cost adder for options.
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Old 02-06-2019, 12:46 AM
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It is not a special order, it is standard equipment for a manual to be ZF6 with a 3.45 in 1991. Nothing special about it.
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