Author Topic: rear diff yolk 9 inch rear size ? (Read 596 times)

GT350 · « **on:** March, 24, 2010, 12:33:11 PM »

what size is a third member yolk on a 69 mustang axle (9 inch)?

66gt350 · « **Reply #1 on:** March, 24, 2010, 02:18:30 PM »

There are a lot of varieties on the yoke that can go on a 9". There's a long and short yoke (the length going towards the driveline) the short one is more common. There's about 1" difference between the two. Then there's differences in the u-joint size, depending on what series of u-joint it takes...1310, 1330, 1350. Which dimension are you looking for?

GT350 · « **Reply #2 on:** March, 24, 2010, 03:03:46 PM »

Quote from: 66gt350 on March, 24, 2010, 02:18:30 PM

There are a lot of varieties on the yoke that can go on a 9". There's a long and short yoke (the length going towards the driveline) the short one is more common. There's about 1" difference between the two. Then there's differences in the u-joint size, depending on what series of u-joint it takes...1310, 1330, 1350. Which dimension are you looking for?

not sure reason im asking is im getting a new diff unit ordered complete with yolk the guy asked me what size of yolk do i want.I dont have an old 3 rd member i bought a casing with shafts only, the car its going into is a 68 mustang so the most common one used in mustangs he gave me 2 sizes 3 1/4 or 3 5/8 ,the driveshaft i have is off a 70 mustang and the diameter of where the u joint goes into is 3 1/2 end to end where the cups fit into. hope im making sense here as its quite confusing

66gt350 · « **Reply #3 on:** March, 24, 2010, 03:17:25 PM »

It sounds like your guy is talking about the u-joint size. It's either a 1310 or a 1330. Here's a website that I found quickly about measuring a yoke for a u-joint: http://www.actionmachineinc.com/ujointmeasuringguide.aspx It should be the same for measuring your driveline to see which u-joint you need. But if you get the wrong one...all is not lost. there are conversion u-joints that are 1310 on one way and 1330 on the other.

When you measured, did you measure outside of the flange to outside or did you measure on the inside of where the clip goes? does that make sense?

GT350 · « **Reply #4 on:** March, 24, 2010, 03:31:10 PM »

i think i got it now,i measured the outside to outside the 1310 seems to be the popular one.

buening · « **Reply #5 on:** March, 24, 2010, 07:00:03 PM »

For my 70 351w with FMX it has the 1310 Special u-joint. Note that Ford had 1/8" larger caps on the differential yoke compared to a standard U-joint of that size, as shown in the website 66gt350 shows. To find the specific U-joint size used for your car, use this website to determine them http://www.mustangtek.com/differential/Driveshaft.htm