my 1968 442 has a type O rearend i have been told its rare is this true i would like any info about it

 

Not so much that it's rare; it's expensive to get parts for.

 

Welcome to the site Del! The type O rear ends were used from 1967 through 1970 and were Oldsmobile only. Came with both 28 spline and 31 spline axles, depending on gear ratio and year. Decent rear ends but as Allan said parts are not as plentiful as years that shared parts with other GM lines. John

 

If you can get underneath your car and look at the passenger side axle housing tube, you should be able to find a two-digit code (either two letters or a letter and a number). That code will tell you what your differential ratio is (unless someone has gotten into it and did some altering). You might have to wire brush the tube to find the code but it should be there, usually facing aft, but sometimes facing forward. There are places on this site that will tell you what that code means or, if you post it here, someone will tell you what it says!

Randy C.
'68 4-4-2 convertible (restored 2007)
'69 4-4-2 convertible (still working on it)