M20 or M21?
Drifting
Joined: Oct 2007
Posts: 1,254
Likes: 5
From: Brown Summit North Carolina
Team Owner
Joined: Jul 1999
Posts: 26,545
Likes: 46
From: Huntersville NC
There is a test you can do. Cruise along in 4th gear at 40 mph and downshift to 3rd gear while keeping speed at 40 mph. The rpm jump to 3rd gear at 40 mph will tell you whether you have a close ratio or wide ratio transmission. Don't have the numbers off the top of my head.
http://forums.corvetteforum.com/1551402384-post13.html
http://forums.corvetteforum.com/1551402384-post13.html
Last edited by PRNDL; Nov 11, 2009 at 10:28 PM.
Melting Slicks
Joined: Aug 2005
Posts: 2,359
Likes: 15
From: Confusion
Le Mans Master
Joined: Jan 2007
Posts: 5,485
Likes: 7
From: Peekskill NY
Here's the numbers on my 70. Should be similar for a 74 Muncie
Trans: M20 P 0M 07 A
P- 4sp muncie
0-1970
M-August
07-day 7
A-wide ratio (standard factory trans)
Vin-70S402011
Trans Casting- 3925661
Small TAG: 3952659 WB
Glenn
Trans: M20 P 0M 07 A
P- 4sp muncie
0-1970
M-August
07-day 7
A-wide ratio (standard factory trans)
Vin-70S402011
Trans Casting- 3925661
Small TAG: 3952659 WB
Glenn
Safety Car
Joined: Apr 2000
Posts: 3,802
Likes: 61
From: Wichita KS
I assume you mean Super T10 as the only Super B(ee) I know of was made by Dodge.
I think the side covers are a different shape between the Muncie transmission and the Borg Warner transmission. The BW side cover is bowed downward on the bottom whereas the Muncie is pretty straight.
Since the Super T10 was used starting in the 1975 model year you would have to suspect yours has been replaced in order for it to be a Super T10.
cc
I think the side covers are a different shape between the Muncie transmission and the Borg Warner transmission. The BW side cover is bowed downward on the bottom whereas the Muncie is pretty straight.
Since the Super T10 was used starting in the 1975 model year you would have to suspect yours has been replaced in order for it to be a Super T10.
cc
Thread Starter
Pro
Joined: Nov 2009
Posts: 642
Likes: 16
From: East Coast
I assume you mean Super T10 as the only Super B(ee) I know of was made by Dodge.
I think the side covers are a different shape between the Muncie transmission and the Borg Warner transmission. The BW side cover is bowed downward on the bottom whereas the Muncie is pretty straight.
Since the Super T10 was used starting in the 1975 model year you would have to suspect yours has been replaced in order for it to be a Super T10.
cc
I think the side covers are a different shape between the Muncie transmission and the Borg Warner transmission. The BW side cover is bowed downward on the bottom whereas the Muncie is pretty straight.
Since the Super T10 was used starting in the 1975 model year you would have to suspect yours has been replaced in order for it to be a Super T10.
cc
Advanced
Joined: Jul 2009
Posts: 59
Likes: 0
It's my understanding that from 70-74, muncies should have the following casting numbers: 3925661 on case, 3978764 on tail. They are all fine spline transmissions- both front and back splines. I believe later years went to a Borg Warner 4 speed.
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Instructor
Joined: Sep 2009
Posts: 150
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From: Glen Allen Virginia
This is stamped on the right side of the case. I am pretty sure that the M21 was not available for the L48. It only was available for the L82 and 454.
Thread Starter
Pro
Joined: Nov 2009
Posts: 642
Likes: 16
From: East Coast
