Underdrive pulley

[moparzrule]

Whats the main differences in an 88' underdrive pulley and 89-up pulley? They are both 5 bolt but is there different spacing? Is the back spacing different on the pulley itself?

I'm swapping from an 88' engine to a commonblock and just wondering about trying to use the 88' underdrive pulley.

[4 l-bodies]

Matt,
IMO, The 88 is just a strange year for crank spockets and pulleys. It was a transition year between the early and CB motors. The 88 crank sprocket is longer than the earlier version. So obviously the crank pulleys needed to be a different size as well. Added to the mix is the TD 2.5 sprocket which is different too. Chrysler made the locating ring on the crank snout different sized in an attempt to make the pulleys non-interchangable. Earlier pulleys and crank sprockets used a larger locating ring, while the later CB motors this ring size was reduced. My advice is try to keep the crank sprocket and pulleys together as a set for the 88 model year, as there are several variations which could get your belt alignment goofed up. I attached this pic to help show what I'm talking about.
At a minimum, I think you will find the pulleys center hole to large on your underdrive pulley. I think the spacing could also be different depending on what crank sprocket you are actually running.
Todd

[moparzrule]

The exact answer I needed, thanks!