| Ronald,
 From what I have found out from my factory manual,  petrol injected
models have a 3.45 : 1 ratio and the carb/usa models have a 3.70 : 1
ratio.  The differential unit did not change due to having or not having
an overdrive.
The ratio of the laylock 'A' type overdrive is 0.82 : 1.
The ratio of the laylock 'J' type overdrive is 0.797 : 1.
Greg Perry
Ronald A. Dowty wrote:
 >Do the differentials have the same gear ratio's for overdrive vs.
 >non-overdrive cars? If not could someone give me a break down of the
 >different ratio's and they're proper year models and which ones I should
 >be looking at. I've got a late model (76) I'm adding a OD to and it may
 >be an A or a J type. I haven't decided and I've actually planning to use
 >a early model frame and A type it or replace the tranny mounts.
 >
 >Anyway, the main question hear is about the differential gears so don't
 >worry about the tranny part.
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