# Identify the ratio on this 14ff from these numbers?

Discussion in 'The Garage' started by BozoWise, May 12, 2002.

1. ### BozoWise1/2 ton status

Joined:
Mar 28, 2002
Posts:
1,224
0
Location:
Lubbock, TX
These numbers were stamped on the ring gear of a 1974 k20 14 bolt FF. What is the gear ratio? I would think it is a 4.l11 but need confirmation. Thanks in advance.

3977334 10 41 1 74 GM 2 C-T

2. ### tRustyK5Big meanieStaff MemberSuper ModeratorGMOTM WinnerAuthor

Joined:
Jul 23, 2000
Posts:
37,318
2,962
Location:
E-town baby!
Build(s):
1
4.10's...built in Jan 74

Rene

3. ### Zeus33rdSmarter than youGMOTM Winner

Joined:
Mar 14, 2002
Posts:
7,324
10
Location:
Grass Valley, CA
The first group of seven numbers I'm clueless about. Bu the next ones I do know. The 10 is the number of teeth on the pinion, 41 is the number of teeth on the ring. 1 means Januarry, and 74 means 1974. All stock GM ring &amp; pinions have the number of teeth stamped on them. You can get the ratio by dividing the 2--Devide 41 by 10= 4.10.

4. ### BozoWise1/2 ton status

Joined:
Mar 28, 2002
Posts:
1,224
0
Location:
Lubbock, TX
You guys rock!

Now for the next question. How can I tell if there was a factory traction device or if it is just an open dif?

5. ### Scooter1/2 ton status

Joined:
Nov 18, 2000
Posts:
551
0
Location:
Grandview, Mo.

Joined:
Mar 28, 2002
Posts:
1,224
0
Location:
Lubbock, TX

7. ### Klef72K51/2 ton status

Joined:
Apr 8, 2001
Posts:
249
0
Location:
Columbia City, Indiana
FYI the first grop of numbers is just the part number of the ring gear. The pinion will have a different group of numbers. Once they are lapped together they become a matched set of gears and will receive another number that is not displayed anywhere other than the blueprints or a parts store.