I picked up a Super T-10 or my son's Nova and was wondering what ratios are in it. The casting numbers are 3-10-81 MLT-11D1 13 04 065 903
FpC4

Does anyone know what ratio gears this thing has? I think it is out of an 81 Z-28. Bob

I'm not sure if the casting number tells you the ratios.

On the input shaft, there should be grooves cut into the splines. Two groves indicate a 2.43 first gear, three groves indicate a 2.64 first gear and I beleive four groves is a 2.88 first gear.

This link should answer your questions.

http://fiedlerh.home.att.net/BW.htm

I was once told there is a letter code on the side of the trans that corrosponds with the gear ratios it has?

No letters on a ST-10. What you have appears to be an OEM GM (Pontiac or Chevy) B/W ST-10 with the aluminum main case, bearing support, extension housing and cast iron side cover. There should be some rings on the input gear like the Muncie: 2 rings=2.43:1 first "S" close ratio, 3 rings=2.64:1 first "W" wide ratio, and 6 rings=3.42:1 first "Z" ratio. If you go up to Richmond gear Catalog - Super T10 (http://www.richmondgear.com/01pdfs/pages33-35.pdf) , it will show their version of these transmissions.

Borg-Warner Super T-10 P-code 2.43 1.76 1.47 1.00
Borg-Warner Super T-10 S-code 2.43 1.61 1.23 1.00
Borg-Warner Super T-10 U-code 3.44 2.28 1.46 1.00
Borg-Warner Super T-10 V-code 2.23 1.77 1.35 1.00
Borg-Warner Super T-10 W-code 2.64 1.75 1.34 1.00
Borg-Warner Super T-10 X-code 2.64 1.61 1.23 1.00
Borg-Warner Super T-10 Y-code 2.88 1.74 1.33 1.00
Borg-Warner Super T-10 Z-code 3.42 2.28 1.46 1.00
Borg-Warner Super T-10 AA-code 3.29 1.72 1.00 1.00
Borg-Warner Super T10 BB-code 4.17 2.28 1.46 1.00
Borg-Warner Super T-10 CC-code 2.88 1.91 1.33 1.00

And don't forget:

Borg-Warner Super T-10 T-code 2.64 2.10 1.46 1.00
Borg-Warner Super T-10 Q-code 2.88 2.10 1.60 1.00

she's got 6 rings, ad I turned th input while counting- about 3.3 turns for 1st so it must be the 3.42 ratio model. looks like te 327 will spin good out of the hole :D