SPID Axle Question

[DBear]

hey guys....on my 71 K10 burb, my SPID has no Axle ratio info on it, and I was looking tonite at the front axle, and there is a tag on the pumpkin cover, which say 3.07. I then looked through a 1971 chevy truck options book, and it shows for the engine, trans combo that 3.07 was standard for that vehicle. I am just a little taken back because this whole time I just figured it had 3.73's. My question is this: if it came originally with 3.73's, would it be on the SPID???