David DeCan

I am going to purchase an M20 4 speed and need to know if they are brand specific? Will an M20 out of a Chevy, Pontiac, Buick all fit my Olds?

Is bell housing brand specific?

How about the shifter and shift rods? I know the chrome shifter is different for the Olds 70-72 with console.

Should I buy a core and have it rebuilt? Doubt there is anyway to know if the trans is good shape.

Thanks for the input.

gregvm

The tranny itself will work from any gm, but there are differences on speedo drive placement on the tailstocks, Olds is toward the drivers side.
Bells are Buick,Olds,Pontiac or Chebby bolt patterns, not interchangeable.
Any shifter should work, but console interference may be an issue with the handle.
Hope this helps.
Greg

joesw31

David DeCan

Application: 1970 Cutlass, 455, Chevy 12 bolt diff. Currently auto.

RetroRanger

If your planning to drive tha car you may want to look at autogear Muncie replacements, brand new 4 speeds w stronger cases and modern machining technology VS 40 plus year old whipped transmission. You can order w fine spline coarse spline and you choice of gearing and output shaft

gregvm

First big problem you're going to have is that the crankshaft MOST LIKELY isn't drilled for the pilot bearing, therefore no manual tranny install.

Been there.

If you're going new, look into the tremec tko-600 5 speed OD.....works great with my 3.73's and the .64 ratio od.

Greg

David DeCan

Thanks for the replies. I looked at the Tremec. Really nice. Too pricey for this driver. Looked at Auto Gear. Again, too pricey.

This is a weekend cruiser.

Need to find a local M20 and pick up the other parts on Classic Olds or elsewhere.

Thanks for the input.
David

David DeCan

Just ran into this Muncie M20 out of a 69 Chevelle.

How do you id that it is an m20?

Will the shifter work in my console 70 Cutlass? Not necessarily the chrome shifter bar, but the linkage and the shifter?

This is what the Craig's List ad says:

"I have a Muncie M20 from a 1969 Chevelle. It has new front shaft bearings and the gears look good. Comes with a Hurst competiton shifter with linkage, new bushings and clips. Also have a longer shifter if this one is too short. You can fab it or whatever to the other. $800."

Thank you.

David DeCan

Just ran into this M20 in Seattle: Ad reads:

"Muncie M20 4spd Transmission $935

200 miles on rebuild Muncie 4spd with Hurst shifter.

Maincase casting number: 3925660
Stamped vin number: 28L101750
P8C14 Mfgr date: March 14, 1968
Type: M20 wide ratio
Rings: Two (or grooves on imput shaft)
10 spline input, 27 spline output, 1" mainshaft

Gear Ratios:
1st: 2.52
2rd: 1.88
3rd: 1.46
4th: 1.00
Rev 3.11"

RetroRanger

I understand the $ issue, but ask yourself this why are people selling rebuilt muncies w only 200 miles on them? The modern autogear trans is arguably 2x the price but running thru the gears hard w 5 k shifts and no grinding or popping out of gear or dropping the trans for a front shaft leak has got to worth something....

David DeCan

RR--I think your points are valid, but I doubt seriously this vert will ever see over 4000 rpms. The rods are stock, valve train is stock, and its just not how I want to use the car. Possibly my age is beginning to show .

I don't think the 455 will top out over 450 HP. Banging gears is probably not going to happen.

Do you think I am asking too much for a rebuilt M20 to hold up and perform well as I will be using the car---Friday night cruiser, Saturday road trip, Sunday back in the garage?

Thank you for your input all.

David

seansolds

you can install a M20 to run to 7,000 rpm I've done this already. No other modifications other than just in stock form. If you want to plant your tires with slicks then the torque will break the case. Then you may want to look into Auto Gear but even the torque may snap that one too. If you purchase any M20 from C.L. Just assume a rebuild and remind the seller unless they can provide receipts and also provide and inspection. I don't just take anyone's word unless it maybe a freind of a freind. Even that's iffy. Nothing wrong with perfectly working M20 it can provide years of happiness.

Sean