70 series cruiser Diff head wanted

fweddy · Post by **fweddy** » Fri Oct 26, 2007 9:40 am

The rear diff in my cruiser is going to take a bit of $ to get in good shape again.

So I'm looking at the option of getting another diff head.

I'm unsure of the ratio off hand (some one here might be able to fill us in) I can get back with that info later.

Consider LSD or open

Its for a full floating back end BJ74.

Let me know condition and $ you are after.

Reply or PM

Thanks

Sadam_Husain · Post by **Sadam_Husain** » Fri Oct 26, 2007 10:51 am

40 and 60 series diffs are the same, most of them are 4.11:1 but there were some early 3.7:1 diffs around but there not very commen.

The 40 series diffs have a different bolt spacing on the driveshaft flange so you'd have to swap your flange over if you pick up a 40 series diff.

edit*
60 & 70# have a round flange and 40# have a square flange

sig · Post by **sig** » Fri Oct 26, 2007 5:23 pm

Yours will be 4.11 ,some of the 60s and 80s came out with 3.7 and some of the late model pickups are 4.3 ,but 85% of cruiser stuff is 4.1 so youve got the most common one around ,tm seems to be a good place .can quite often pick up a lsd for under a couple of hundy if you keep your eyes open.

fweddy · Post by **fweddy** » Sun Oct 28, 2007 8:15 am

Yep can confirm it's a 4.11

Am on the hunt at present. Got a couple of leads but are non-lsd

Any other info appreciated. thanks

fweddy · Post by **fweddy** » Mon Oct 29, 2007 9:16 pm

Just been to look at a diff head. I counted 37 teeth on the crownwheel and 10 on the pinion - that makes it a 3.7 right? apparently it came from a 70 series. he also has a 40 series diff but its in the casing and was unable to check the ratio. He said it was from a 3 speed 40.

muddy · Post by **muddy** » Tue Oct 30, 2007 5:59 am

An older 40 may also have 17 spline axles...