'69 L46 Gear ratio

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Oct 7, 2008 | 04:53 PM

split71

Thread Starter

Racer

Joined: Mar 2007

Posts: 307

Likes: 2

From: Port Orange Fl

'69 L46 Gear ratio

What would is the standard gear ratio w/ 4sp for a 350hp car? Would the M20 be the standard 4 speed with the M21 being optional?

TIA,

Mike

Oct 7, 2008 | 07:06 PM

LT-1 kid

Melting Slicks

Joined: Sep 2007

Posts: 2,149

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From: cary Il

i had a 70 350-350 and the standard gear for a m20 is a 3:36 and m21 would be a 3:70. m20 would be standad, 350 hp only avalable with manual trans only.greg

Oct 7, 2008 | 07:09 PM

wfo76

Drifting

Joined: Sep 2006

Posts: 1,259

Likes: 2

From: MS

I believe the 69 order form just said something like "L46, requires either M20 or M21 4-spd" so you had to pick one.

M20.....3.36 std, 3.55 opt
M21.....3.70 std, 4.11 opt

For 70-up after the 3-speed was dropped, the M20 became standard but it wasn't in 68 and 69.

Oct 8, 2008 | 07:50 AM

split71

Thread Starter

Racer

Joined: Mar 2007

Posts: 307

Likes: 2

From: Port Orange Fl

Thanks for the replys, I guess I have to figure out which tranny the car has. This is a car I'm going to look at on Saturday, 2 owner Riverside gold/black interior coupe in what looks like nice driver condition.

Mike

Oct 8, 2008 | 08:30 AM

wfo76

Drifting

Joined: Sep 2006

Posts: 1,259

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From: MS

If you can see the tranny stamp on the passengers side, starts with a P and ends with either A (M20) or B (M21),
early 69's won't have the A or B.

Also rear end codes stamped under the differential,

M20
AK - 3.36 open (std)
AM - 3.36 posi (opt)
AN - 3.55 posi (opt)

M21
AS - 3.70 open (std)
AO - 3.70 posi (opt)
AP - 4.11 posi (opt)

Oct 8, 2008 | 08:39 AM

GTR1999

Tech Contributor

Joined: Aug 1999

Posts: 15,173

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From: Connecticut, USA

Almost 40 years later, there could be anything in there. Many diffs were swapped or blown up over the years. Look at the housing date code and see where the RPM is @ 60 mph.

Oct 8, 2008 | 09:35 AM

split71

Thread Starter

Racer

Joined: Mar 2007

Posts: 307

Likes: 2

From: Port Orange Fl

wfo, great info!

While I agree anything can happen in 40 years this car looks unmolested...I guess I'll find out when I look at it.

Oct 8, 2008 | 10:49 PM

PRNDL

Team Owner

Joined: Jul 1999

Posts: 26,545

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From: Huntersville NC

you can easily tell if the trans is M-20 or M-21 by driving it. Drive along slowly in 4th gear and shift down to 3rd while keeping the speed constant. Note rpm in 4th and rpm in 3rd and you will know if it is wide ratio trans or close ratio trans.