[289ACE]

From the CSXinfo.net website;

Differential
The differential used was a Salisbury manufactured cast iron IRS third member. This differential is the ancestor to the currently made Dana 44, sharing the same internals. Final drive ratio was 3.54 on the early cars, the was changed to 3.77 on later cars in order to limit top speed. All cars used telescoping half shafts with two u-joints each sending power through the cast iron uprights.