1968- fine splines mean birfields? (1 Viewer)

[MOfj40]

I'm looking at an aussie locker for the rear of my 68 40. I've not checked to see if I have 10 or 30 spline axles, so I'm going to pop the diff cover and see this weekend.

Question- If I find fine splines, would this indicate birfields instead of ball and claws? Or did the spline and birfield upgrades happen in different production months?

I'm 90% sure my drivetrain is original 68, but the truck is titled as a 74 and the frame number has been removed, so I don't know what month of 68 it was made.

Thanks.

 

[woody]

if the side gears are fine, you have a 99% chance of the fronts being coarse birfs....assuming the PO didn't muss things up for ya....

IIRC, the Aussie is only available for 30-spline sides, and I would NEVER EVER consider purchasing/installing a coarse spline locker....EVER. If you find coarse spline axles, put them up for sale and purchase a pair of used fine's.

 

[MOfj40]

If I find coarse splines, I've got a source for an axle swap. I'm just crossing my fingers and hoping to find fines.

How well do the coarse birfields hold up compared to fine birfs? I'm running a stock F with 33s.