C2 - slight whine in first gear
 

New to me and first ever GM product - 65' C2, 4 speed. It has a slight whine in first gear, natta in 2,3,4. Is this typical, or the beginning of an issue. Match number tranny with 70,000 miles.

Unless it's the M22, aka Rock Crusher, then I would say it's probably not normal.

How do I identify if M21, M22, etc?

I don't know of any way to externally identify the transmission type. It might be possible if you had the dust shield off and could see the clutch pressure plate. Then you could put it in gear and have someone rotate a rear wheel and monitor the Revolutions of the clutch plate. Of course that would require a third person inside keeping the clutch depressed so you weren't trying to turn the engine over at the same time. IIRC, the low gear ratio is about 2.5 to 1 (M20) and the low gear ratio is about 2.2 to 1 (M21 & M22). The reason the M22 is called Rock Crusher is because it utilizes straight cut gears and is therefore a lot sturdier.