M-20 with L-78 or L-72 & deep gear -How?

[camaromb]

I recently sold an unrestored '69 Z28 with original M20 trans and 4.10 rear. It had great pedal response at low speeds unlike any other Z I have owned.
There was also at least one Canadian Copo Camaro built with an M20 trans.
Mark

[Pantera]

My '69 L-78 7,400 mi survivor Nova has the build sheet showing a M-20 but the tranny does not have a ring around it?

It also has a 3:36 rear.

Could it have been replaced with new gears under warranty?

Trans Case has all the correct numbers on it.

[JRSully]

My original 69 L78 Nova has an M20 on the build sheet, and was ordered and still has the original 4:56 rear in it (gear change was necessary to say the least) SULLY

[WILMASBOYL78]

I think the M-20 was the std trans unless you ordered the M-21, at least in the world of Novas. My red 70 is a strpped down car, sold off the lot and has 3.55 w/M-20. The other 2 were ordered cars with more options and both came with 3.55 and M-21. The 68 and 69 cars are both M-20 with 3.55 gears. The M-21 seems to be better suited to gears 3.55 and up in the BB cars. Just my two bucks worth.(inflation)

TW

[Schonyenko2]

I think the M20 is what you got if tou did'nt specify something else. I ordered my 70 with buckets, console, 8 track etc, so It was'nt a striped down model and it came with the M20. I did'nt mind the M20, but the Muncie shifter sucked. Schonye

[YENKO DEUCE REGISTRY]

I agree with Wilma there, M20 was standard unless you ordered the M21 or M22 regardless of rear gear.

[NCGuy68]

And I agree with Marlin.

The paperwork on my Van Nuys 68 Z28 shows the M21 and 4:10 gear as optional selections. Standard Z28s' usually came with a M20 and 3:73 gear.

On the other hand, I have seen a documented 68 L-78 with a 3:07 non-positraction gear and a M22. Seems that GM cooked up some unusual combinations at the time. Original documentation and/or carefully decoded numbers seperate the originals from the clones.

[Paul_S]

Thanks for the responses. Keep'm coming.

I was looking on CRG's site for info. They don't get very detailed, but they do list what was available in a chart. (I'm not sure how accurate it is, but it's getting a little closer.) I'd like to see some info and details from original documents to back it up and for the other years/cars.

For '67
Z28: M-21
L-78: M-13 (3-speed), M-21

For '68
Z28: M-21, M-22
L-78: M-13, M-21, M-22

For '69
Z28: M-20, M-21, M-22
L-78: MC1, M-20, M-21, M-22
L-72: M-21, M-22

[Kurt S]

I was going to do some digging before I posted, but the above post drew me in.

That info is correct for Camaros (except L72 could get M20's, I'll correct that). I'd need to do some digging to find the backing documentation, but the jist of it is the M20 wasn't available in a Z or L78 in 67 or 68. In 69, any Camaro could get an M20. Not sure of the logic behind it and have no idea on other models.

[mssl72]

This topic is something I have been dealing with recently. A lot of questions have come up, some got answered, others created.

The 1966 Finger Tip Facts book and 1966 Motor Vehicle Price Schedules book both have a page with all the "Power Teams" listed. It shows the engine, transmission and rear axle ratio combinations that could be ordered. I'll list a few examples of what it shows. For Full Size Chevrolet and L72, 427/425hp you could order a 4-speed close ratio (M21/22) with 6 different gear ratios ranging from 3.31-4.88's. If you wanted a wide ratio (M20) 4-speed or a Special 3-speed (M13) it lists only 3.31's, nothing else. The 3.31 ratio was considered standard equipment. In 1966 for a Chevelle ordered with an L78, 396/375hp you could order a 4-speed close ratio with 7 different gear ratios ranging from 3.07-4.88's. If you wanted a 4-speed wide ratio or Special 3-speed you had 5 different ratios ranging from 3.07-4.10's. In Chevelles 3.73 was standard equipment. Corvette with L72 shows only close ratio being available with 4 gear ratios ranging from 3.36-4.11's, 3.55's being standard.
So, for example, why could you get a wide ratio 4-speed (M20) and 4.10 posi in a Chevelle and not in Full Size Chevrolet? Why only close ratio in a Corvette? How did Chevrolet decide things like this? I didn't think that the gears you wanted would effect the transmission you could get. I also found that POP's could tell you Muncie, but not which one. You would need a build sheet or window sticker. I don't have anything on the 1967-1969 model years, but I would love to see what was going on in the same books for those years.