IIRC, the '76 Firebird MPC corroborates the lack of TCS on the HO.
I'll PM my number shortly.
There is a restored '74 Camaro M21 trans on ebay.
P4M10B, partial VIN 14N156267 (August 10, 1973 assembly date)
Side Cover: 335308
Has the later cast date marking on the side cover but not a complete pic of it so not sure how it compares with other pix I've been receiving.
Seller says "with correct side cover 335308" but that doesn't necessarily confirm that the trans was restored with its original side cover or if the builder put a 335308 cover on it believing it to be correct.
It does have the TCS on the 3-4.
It looks like early castings of the 335308 have the two 1/2" dia. circles as the date and status markers but at some point, a different larger circle was used with the year in the center. Looks like the 1/2" circles remained on the casting but unused for a time and then began to disappear. I'll need to see a lot more of them though to get any kind of handle on what I'm seeing so far.
Got no reply from Paul Cangialosi about the long vs short boss with respect to the 335308.
Based on what I observed/measured, I am convinced the 335308 is a SHORT boss cover, the published references got it wrong. Unless someone has evidence to the contrary, I am convinced the 3952648 is interchangeable with the 335308 for all applications that only required the 3-4 TCS location and there is no different in the length of the Shifter Shaft bosses between these two covers.
Roger, the 335308 you have with 2 switches installed seems odd. I cannot think of any application that would make use of 2 TCS switches. And if one was used as a Neutral Safety Switch (it's just a switch so wouldn't necessarily be used in the TCS circuit), I can't understand how it could be used for that purpose by itself. I think it is more probable that somebody added a 2nd switch to match to their application, for example, an early Pontiac trans with a 1-2 TCS switch subbed into a '74 application that needed a 3-4 TCS.
Even possible that this trans was OE in a late production Pontiac that was still in inventory when the March 15 redesign went into production. Pontiac could have added the 3-4 switch and just left the 1-2 switch in the side cover, but not connected.
All to say, I can't think of an application that would make use of switches on both the 1-2 and the 3-4. Maybe somebody has encountered such a thing? But given that the Muncie experts (folks that are probably most familiar with Chevy applications of the Muncie) seem to be unaware of the 1-2 boss ever being drilled and tapped, I'm guessing the only application that ever needed the 1-2 boss drilled and tapped was the early '73 Pontiac.
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