I want to replace the AOD in my 66 with a T5. Will I need to shorten or lengthen the driveshaft and about how much?  

KG, when you look at the aftermarket aluminum shafts for late model Mustangs they are the same length for T-5 or AOD. I have one in my '90 Mustang w/ AOD and the FRPP catalog says it fits T-5 as well.

With that said, I would ASSUME that when you swap the AOD for the T-5 in your classic Mustang the driveshaft length should not change.

HTH...
Mark  

Mark,I haven't figured out the difference between the 3 replies so I'm not sure where this is going.Thanks for the info in the Ford Racing SVO Motorsports catalog.My AOD case is 30.5 inches long plus 1" of output shaft beyond the seal. My 51" alum. shaft is about .5 too long from what I have read.To help the problem out I ground off the chamfer on the output shaft.With that mod I have 1" of slide at the yoke at normal ride heigth.So if I could get a good OAL on a T5 with or without a bellhousing it would be helpful.Ihaveabellhousing. thanks KG  

Mark, I found T5 length and a lot more at dandperformance.com which you mentioned in another post.  Thank you, KG