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Does any know if the 68-69 427/435 L71 was ever available with an automatic transmission? I don't know of any suffix other than "IR" (4 spd) but I ran into some guys at a Vette cruise who claim that the auto trans was available on the L71?!?! If so, what would the suffix be?
The letter from GM that I saw years ago claimed that 255 “special” M-40 automatic transmissions were produced for use with solid lifter big blocks in Corvettes in 1969 only. This would include L-71, L-71/L-89, L-88, and L-88/ZL-1. Unlike their metal body counterparts with the M-40 which could ordered with as high (numerically) as a 4.10 rear axle ratio, the steepest rear available with a Corvette M-40 was a 3.36 which was listed as the “performance” rear axle.
The automatic solid lifter cars are rare, but they tend to be not as desirable as their manual transmission counterparts.
To add to Stans info, the M40 found on the solid lifter motors in 69 was special in that it had a higher stall speed converter and may have also included other HD internal items. The trans itself was coded differently as well. CY maybe? It also was more expensive than the standard M40 found in other Corvettes. I don’t have the price difference in front of me but it should be easy to find.
I only looked at the 1969 broadcast codes, but the MR code for the 1969 L-88 is wrong... That's the code for the early, closed chamber head L-88/M-40 combination (not M-22).
Here is the GM letter Stan mentioned on M40 L71 and L89 cars. I agree with you Stan, the M40 cars are more rare, a blast to drive but they don't bring the money at the 4 speed cars do.
Thanks for posting that Jonathan. I saw that letter over forty years ago… Knew that I didn’t imagine it.
That letter came with a 1969 L-71/M-40, Monza red/black, no radio, coupe. Had about 19,000 miles on it at that time. It’s come up for sale several times over the years so I know it is still around.
The CY was the HD T400 trans.
There was a higher stall speed convertor included, but I do not remember the stall rating.
IIRC the convertor had extra bolts to the flex plate.
I do know that the mechanical governor controls the WOT **** point, and they were programed higher, more like 6500 rpm, even in drive. They were pretty much ideal.
The normal shift point was more like 5000-5500.
The 1970 Z28 auto had the same setup.
We modified the governors of several cars in the shop, with std T400s, to shift higher like that.
I once drove an LS6 automatic with its original CY transmission. I was shocked how hast it was. The transmission would downshift at the touch of the throttle and chirp the gears. And shifted right on cue at redline.
I am just finishing up a frame off on my 1969 L-71 Auto, original engine, trans, & diff, photo of NCRS certified tank sticker, and photo of tag on side of trans. So L-71 Auto's are real, but not many out there. Thanks, Jim
JIm,
I know the car well, it was delivered new at a dealer in Michigan. I was close to buying the car from the past owner. Glad to see it getting restored!
I have an LX code L-71 engine, 6-bolt convertor, and matching CY trans sitting here. I'm currently looking for a body to put it in or might sell it as a complete package next summer.
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C3 L71 available w/auto trans?
