Need rearend ratio help,1975 K20
 

I went and looked at a 75 Chevy K20 today. I could not find the code stampings in the rear axle tube(figures I'm the one always telling people to do that!). The option sheet in the glove box did not list a rearend ratio as an option so that means it is standard ratio for a v-8 truck. I do not have a 75 dealers brochure so anyone that does tell me what they list as standard ratio please. I hope 4.56 like it was in 73. thanx , DAVE

mines 3.42
 

mine is a 79 lwb k10 and my original ratio is 3.42 with a th350. the ratio will depend on 2wd 4wd motor and trans combo.
hope that helpes a little