Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

Am I looking at 3.07 gears?

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by Scrubby, Nov 16, 2003.

  1. Scrubby

    Scrubby 1/2 ton status

    Joined:
    Dec 1, 2001
    Posts:
    114
    Likes Received:
    0
    Location:
    Boise, ID
    I just picked up a '72 blazer with a 350/TH350/np205/12 bolt. The glove box says nothing about gears, and from everything I have read I probably have 3.07 gears? Am I right?

    If it wasn't pouring out side I would be cracking the cover on the diff right now.
     
  2. Beast388

    Beast388 1/2 ton status

    Joined:
    Nov 6, 2001
    Posts:
    3,039
    Likes Received:
    0
    Location:
    Clinton, IA USA
    *EDIT*
    IIRC, the 3.07 ratio was standard. The option sticker in my '71 Burb listed my 3:73 option. So, in answer to your question....yes, probably the 3.07 ratio. /forums/images/graemlins/thinking.gif
     
  3. R72K5

    R72K5 Banned

    Joined:
    Mar 5, 2001
    Posts:
    8,905
    Likes Received:
    0
    Location:
    central IL
    actually 67-72 std equipment installed C and K 5 and 10 series trucks axle ratio was 3.73 for all models and into alot of the rest of the '70s too,

    3.07 you got when you ordered something else optional like the 4 speed or an auto trans with a 350 engine, etc. sometimes even with 307 engine

    you should pull cover and look along outer skinny edge of ring gear for the stamping codes, the teeth count of both gears will be listed divide them to get your ratio

    rear will be same ratio unless somone did something stupid


    no one can simply say that you have 3.07 or that you have 3.73

    you will have to pull cover and look, or get stamping code off pass side top sid eof axle tube about 4" from edge of pumpkin housing axle tube neck and turn that code into local chevy parts counter and have them look it up for the year make model of truck that its from and hope that gears never have been changed in that axle or that wont be accurate either


    plus 3.08 was not truck ratio, it was 3.07 back then
    ratios you saw in these trucks:
    3.07, 3.73

    no 4.10 or 4.11 in half tons yet, apparently a few years in the 73-80 range there was a 4.11 ratio you could get somehow with certain engine or drivetrain order
     
  4. Stroked72Blazer

    Stroked72Blazer 1/2 ton status

    Joined:
    Nov 9, 2002
    Posts:
    352
    Likes Received:
    0
    Location:
    Little Rock, AR
    Asuming this is not a posi find some way to hold one end still (as if you only jacked one tire off the ground) and turn the other tire 2 full turns while counting how many times the drive shaft (yoke) turns. If it turns just over 4 times then it is 4.10's if it turns 3 and 3/4 times it is 3.73's just over 3 times is 3.07's so on and so on. If it is posi jack both sides up and turn one tire one full turn and the counts should be the same.
    Notice you just covert the fraction to a descimal. True it's not prescise and wont tell you if you have 3.07 or 3.08 but it will get you close and let you know if you have 3.07 or 3.73.
     
  5. Beast388

    Beast388 1/2 ton status

    Joined:
    Nov 6, 2001
    Posts:
    3,039
    Likes Received:
    0
    Location:
    Clinton, IA USA
    Randy....IIRC the 3.07 ratio was standard with the 350 engine...which he has. The 3:73's had to ordered with the 350. /forums/images/graemlins/thinking.gif /forums/images/graemlins/thinking.gif
     
  6. Blazer1970

    Blazer1970 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    1,600
    Likes Received:
    0
    Location:
    Old Mission, MI
    [ QUOTE ]
    Randy....IIRC the 3.07 ratio was standard with the 350 engine...which he has. The 3:73's had to ordered with the 350. /forums/images/graemlins/thinking.gif /forums/images/graemlins/thinking.gif

    [/ QUOTE ]

    You are correct. 3.07 was standard with the 350 engine.
     

Share This Page