Is this an aluminum or steel driveshaft. It came of an 88 Vert and weighs about 10 or 11lbs.

 

its stock,that Is what I can tell ya.Probably thin walled steel.
link to Mazdatrix: http://www.mazdatrix.com/g9.htm
show the aluminum shaft is 10.65lbs.

 

what is the cup on the yoke for?

 

It goes over the tail stock and prevents dust and debris from going near the tail shaft seal on the trans.All stock shafts have this.

 

rust=steel.

 

 

Thanks guys

 

If a magnet sticks to it (look on your refrigerator), then it's steel.

 

Please, do not post false information... Especially since you probably didn't even read most of the thread. It has already been determined that the pictured driveshaft is steel.

 

and mazda never produced an aluminum driveshaft, if you happened across one of the aftermarket ones the easy telltale is: the shaft itself is generally about double the diameter of steel stock shafts to make up for the weaker materials, a magnet sticks to steel and not aluminum and the aluminum shaft is several pounds lighter. just about everything on an aluminum driveshaft looks much sturdier because it has to be, if that pictured shaft was aluminum it would eventually egg out the u-joint holes.

 

Its rusting so yea steel