1966 L72 Biscayne

[fsc66]

I sent Leigh a message, curious as to what he will have to say

Paul

[mssl72]

He has these cars on his list.

[fsc66]

Yes, if you had an L72 motor the only Transmission available were the: M13, M20, M21 and M22. Pretty sure what we were saying was if you had a 66 Full Size with a 2Q code (M21) on the trim tag, it has to be paired up to an L72.

[mssl72]

Paul, I wasn't disagreeing with that fact. Just passing on some facts that I did some digging on along with some great input from Leigh.

[SPEEDYB]

Please note that BOP run plants like Wilmington Delaware
cars have "no" trans code on the trim tag.fortunately
My Wilmington produced L72 has not only a build sheet
but also its born with Engine and rear end.

[mssl72]

Speedy, thanks for confirming on BOP plants doing things differently.

[jeffschevelle]

Originally Posted by LT1vette

I knew they were available with all 3 trannies. M20/21/22 Contrary to what the GM literature and Paul say.
I know the owner of 1 of the M22 cars. Almost every option on that car...

Paul never said that you could not get an M20 (or an M22, or an M13) with the L72 engine. He said (correctly) that you could not get an M21 (in a full size car) behind any engine except the L72.

The "literature" he posted says the exact same thing. Go back and look at it again. It shows "4-Speed Close-Ratio" and "4-Speed Wide-Range" and "Special 3-Speed Full-Synchro" as available transmissions behind the L72. (M22 was never listed in the showroom materials in 67 or earlier, hence why so few were built.)

The point is simple: 2Q means M21. M21's only came behind L72's (in a full size car in 66). Therefore, 2Q necessarily means the car came with an L72.

That does not mean (and no one ever said) that every L72 must have 2Q on its trim tag. An L72/M13 or an L72/M20 would not have 2Q. And even some M21 cars (depending on where built) were not coded 2Q.

But if 2Q IS on the tag, it was an L72.

[jeffschevelle]

Originally Posted by mssl72

I had a conversation with Leigh Scott (who is a '66 Full size fanatic and retired GM 35+ year employee) about it and he said;

"All transmissions in 1966, except for Muncies, the speedo cable came out on the drivers side. The Muncie for '66 came out on the passenger side. In 1965, for the M20 Muncie, the speedo cable came out on the drivers side, the M21 came out on the passenger side, hence the reason (I believe) for the "Q" to denote the close ratio M21 and the need for the passenger side speedo cable clip on the floor pan. Old habits die hard, so that's why I think the "Q" lasted for 1966.”

He also mentioned that the rear axle gear ratio had an impact on if the trans would be close or wide ratio. It seemed that cars with low gear ratios got wide ratio transmissions. Paul (fsc66) posted documentation to reflect this as well.

The 2Q explanation above is correct, except that the 1965 Muncie M20 switched to the passenger side speedo cable around the beginning of the 1965 calendar year. That should not have created a problem since all passenger car M20's were Muncies in 65 (except Corvairs). So they just needed to recode 2L as requiring the passenger side speedo.

But it does not appear that that actually ever happened, which is when the confusion around the 2L and 2Q began. I have seen numerous factory M20 65 Chevelles built after 1/1/65 (including many Z16's) that have a cable clip spot welded on the driver's side floor pan, and another one screwed on on the passenger side (which would have happened on the assembly plant side, not in Fisher Body).

The confusion continued throughout the 66 and 67 model years, but it got even worse in 66 when the Saginaw M20 came out, which has a driver's side speedo cable. So now you had some 2L cars with the cable on the left, and some on the right.

For Chevelles in 66 that was not an issue, except for ElCaminos. In all body styles except the Elc, only SS's got Muncies in 66 because all small block M20's were Saginaws. So if the trim tag was a 138 series with 2L, then Fisher Body knew it was a passenger side speedo. If it was 132, 134 or 136 with 2L, then Fisher Body knew it was a driver side speedo.

But on a 66 V8 ElCamino (134 or 136 VIN'd) with 2L on the tag, Fisher Body had no way to know which speedo clip was needed unless they checked the engine RPO for the car on the broadcast paperwork, to see if it was a big block or a small block. For that reason it is common to see 66 and 67 Elc's with the Saginaw clip spot welded on the driver's side (by Fisher Body), and another clip hand-welded along its edge to the pan on the passenger side (which probably happened on the assembly plant side, and not in Fisher Body), or sometimes screwed on (which would have happened on the assembly plant side, and not in Fisher Body).

The situation got worse for Chevelles in 67. With the return of the L79 engine (which received a Muncie if a 4-speed was ordered), there was now the possibility that ANY model number (even a wagon) could be coded 2L for a Saginaw or 2L for a wide ratio Muncie. So again it is common to see a 67 2L car with both clips.

But just like for the 66 big car L72, there is at least one absolute truth around the 2Q code for 67 Chevelles - If a 67 Chevelle that is not an SS and not an ElCamino is coded 2Q, then it came with an L79 engine. (A 2Q Elc could be an L79 or a 396.)

As to the axle ratio discussion, the order forms in 66 did not have two different boxes to affirmatively choose between a wide ratio or close ratio 4-speed. So if you ordered an engine that could be paired with a Muncie M20 or M21, and just checked the 4-speed box on the form, you got whichever ratio Muncie that Chevrolet determined was best for the engine / axle combo the car was ordered with.

But you COULD override that default choice and specify whichever ratio you wanted if the salesman knew to write it in the Additional Options / Special Instructions section at the bottom of the order form, with one exception -- you could not get an M20 with a 4-series axle. 4-series axles required an M21 (or M22).

Then in 67 they changed the order form to give two different lines and check-boxes for the wide ratio and close ratio transmissions, so the salesman could more easily specify what the customer actually wanted.

[TAR6569]

And Framingham and Norwood used 2L for both M20 and M21 in 66, which adds to the confusion!

[TAR6569]

Originally Posted by SPEEDYB

Please note that BOP run plants like Wilmington Delaware
cars have "no" trans code on the trim tag.fortunately
My Wilmington produced L72 has not only a build sheet
but also its born with Engine and rear end.

I'll have to check my list to see if it's entered. Can you PM the last 6 of the vin? I have a number of 66 Wilmington L72's in my list.