Will a 68/69 chevy 12 bolt fit in my 65 f85?

 

Yes, the 68-72 is probably 1.25" wider, only 5/8 on each side. and you'll need a special u-joint.

 

Or a 64-67 Chevelle driveshaft. Henry

 

You can also use a yoke from a Canadian 12-bolt.Those have a yoke that looks identical to the BOP 10-bolts & the 12-bolt O-axle,& uses the same style U-bolts & nuts to fasten the u-joint.
Do you know what the 12-bolt Chevy rear came out of?
Yes,all of the control arm mounts,spring mounts,& shock mounts are the same.Your existing coild springs will fit right over the raised cups on the later 12-bolts,or any other A-body rear(72-older).Yes,the 68-72 12-bolt Chevy rears are 5/8" wider on each side,so it will push your existing wheels outboard 5/8",so check to make sure you will still have good tire clearance.If it is a project,& you will be ordering new rims,then just make a note to get something with a deeper backspace,so you can recenter the wheel under the car.