A couple M6 questions
 

What was the first year that received the better M6 trans?

Will the M6 from a LS1 car bolt into a LT1 car and to the LT1 motor?

Thanks

I found this chart that lists the various applications of the T56

Borg-Warner T-56 transmission - Wikipedia, the free encyclopedia

So it looks like the only weak T56 was the 93, rated 350 lbs torque

Oh good! Anything else you need help with? ;)

So the LS1 tranny use different wiring and speedo hookups?

Yes,

The weaker trans was not a MN6 it was the M28 there is also a M29. They are not really weaker persay. They have better first gear ratios but because of that the transmission sees more internal torque. So the parts are not really weaker as much as the design creates more stress. First gear in a M28 is 3.36:1 while first gear in a MN6 is 2.66.

So if you put a M28 transmission in a 94 that has 3:42s in it it would be about the same as adding a 4:11 Rear.

The simple answer is yes, no, and it depends. The input shaft of the LS M6 is longer than the LT's. Clutch setups are different too.
This may help: LT1 to LS1 T56 swap

Thanks