the e3 bell used in 83-85 mustangs accomodated a 10" clutch whereas, the e6 bell used in the 86-93 mustangs accommodated a 10.5" clutch.....that's the difference that I know of between the two.

Both bells have the same bolt pattern......

TremendousWand wrote:

Yea I think I read that somewhere. So this begs the question, can I use a 10.5" clutch with the e3?

 no

FWIW, I did some quick searches.  There are two parts - first - you need a 10.5" flywheel.  The 10" and 10.5" have different bolt patterns and even threads so if you are dealing with an early bell housing and also the early flywheel, you have to change the flywheel at a minimum.  Second, the key word is "MAY" fit.  One site had a person that had done several 10 to 10.5 conversions on 84's and 85's.  I think the wording he used was "hit or miss" or that the earlier bell housing MAY fit.  Some worked and others required clearancing.  The safe answer here is indeed no when considering the original design it is not 100% certain.  So, put it all together and see if your bell housing is one that fits and have at it.  If it doesn't, then you need to consider whether the clearancing that would be required could compromise the integrity of the bell housing.  In this era of litigation what is someone supposed to say - grind away - I'm sure it will be OK?  The safe bet is to use the parts that were designed to fit the application.