I know that the M29 came in the 93's and that the T-56 came in 94+. I was under my car the other day and I noticed that the transmission crossmember said M28/M29 and then when I was reinstalling my center console in the car it said M28/M29. Anyone know what it says that instead of T-56?

 

Probably because there was no reason to re-tool or re-cast the parts because they are the same for use with the MM6 (T56).

 

The '93s came with M28 and M29 transmissions (depending on rear gear ratio). These are both T-56's, but have different ratios (and lower torque ratings) than the '94-up T-56's.

I'm thinking that GM just didn't bother changing their nomenclature throughout the whole production process, even though every T-56 from '94-'02 was called the MM6. These Mxx are option codes, BTW.

EDIT: shoebox beat me to it!

 

Learned something new here.

Didn't know that there were two different trannies in 93. Thought there was on one......

 

Here's some info, courtesy the FAQ at www.f-body.org

Year Model/Optn 1st 2nd 3rd 4th 5th 6th Final
---- ------------- ---- ---- ---- ---- ---- ---- -----
1993 Manual/M28 3.36 2.07 1.35 1.00 0.80 0.62 2.73 (GU2)
1993 Manual/M29 2.97 2.07 1.43 1.00 0.80 0.62 3.23 (GU4)
1993 Auto/MX0 3.06 1.63 1.00 0.70 -- -- 2.73 (GU3)
1993 Auto/MX0 3.06 1.63 1.00 0.70 -- -- 3.23 (GU5)

1994 Manual/MN6 2.66 1.78 1.30 1.00 0.74 0.50 3.42 (GU6)
1994 Auto/MX0 3.06 1.63 1.00 0.70 -- -- 2.73 (GU3)
1994 Auto/MX0 3.06 1.63 1.00 0.70 -- -- 3.23 (GU5)

Year Model/Optn Torque Capacity
---- ---------- ---------------
1993 Manual/M28 360 lbs-ft
1993 Manual/M29 400 lbs-ft
1993 Auto/MX0 400 lbs-ft

1994 Manual/MN6 450 lbs-ft
1994 Auto/MX0 400 lbs-ft

*Note that from '94-'97 there were no changes to the T-56s. LS1 T-56s have their differences (input shaft, etc.), but I believe are internally identical. Sorry for the messy copy/paste.

 

I kinda figured they didn't bother changing their castings. Thanks guys.