Well I tried to post before but can not seem to find out where the heck it is to see if anyone answered.
I have a 4.56 8 3/4 third member drop out. Seems to be an original 4.56 geared 742 case... the power loc is also date coded 64.

CAn anyone tell what this rear might have been installed in and what factory cars came with 4.56 gears in 64? Thanks foir the help. Jim

To my knowledge no cars came factory equipped with 4.56 gears, they were listed as a "dealer installed" option. Is there a date stamped in the ring gear?

Max Wedge and Hemi cars came standard with 3.91 gears.

Most 4.56 gears likely came in trucks in '64.

Back then you could buy a factory built third-member over the counter.

I have an OEM 3.42 geared, 742 case with Detroit Locker. It has a '64 date code and the case is even stamped "3.42 NS" (No Spin) in the correct location and font for the year.

The standard nomenclature for a third-member equipped with a traction differential in the early '60s would be something like "3.91 S" (Sure-grip).

Here are some pictures

Gears are 64 and power loc is 64 looks to be matching. I do not know how to tell dates on the cases 742 489 etc. Jim

pics

another

ring gear

large yoke

Other than the rough condition, that is an interesting piece.

Are any numbers stamped on the raised pad at the base of the casting?

looks as if it had pinion probs before and chewed it up some

yeah, dos look the pinion was "eating" some of the carrier

To my knowledge no factory car came equipped with 4.56's but the gears and the whole 3rd member were available for "dealer installation". It was probably sold through the parts room.