3 bolt to 4 bolt gear difference

[NOSNUSE]

I have finally got a 4 bolt: and was wanting to know if there is possibility that the gear ratio in the 4 bolt will be different then the one in the three bolt, and how to tell?
Thanks for the help, Keith

 

[zac83]

take the cover off of both. look at your ring gear (tha big one...) mark one of the teeth (on the side, not on the contact face of the teeth...) with something (white out, a dab of grease, a dot of the white crap they use in JB weld, ... ANYTHING that can be used to keep your place..) and count the teeth in both units. if your old one has the same number of teeth as the new one, its all gravey. fair warning, the autos had a different ratio, so if your on a 5 speed car and put an automatic 4 bolt rear in, you'll screw up your center dif (the spider pointed towards the passenger side AND the inner shaft going from the spider to the viscous coupling from the spider weld to the center dif casing cover) which is an expensive part....

basicly if you have 43 teeth, you have a 5 speed, 39 teeth is an auto rear end. if its a rear end from japan, buyer beware, they had some odd ratios that didnt match anything made in america.

 

[NOSNUSE]

I appreciate the answer and time to answer this questions. I wonder about the auto and manual rears being differnent.

thanks, keith