B4 diff in B3 box

[Mja75]

Is it possible to fit a B4 diff in B3 box?
I've got two ball diffs for my B3 but want to swap over to a gear diff for carpet. Unless the B3 ever came with a gear diff will a B4 one fit?

[jwscab]

No. The trans cases are very tightly designed to the diff gear and the diff gears are different sizes .

[Ronbo]

I thought the B4/T4 top shaft could fit to use the newer slippers in the B3, or is that just for the stealth gearbox? i too am planning on running a b3 in 40+ mod for fun, 10.5 to start ... i havent tried it yet to see. i have a plain T4 gearbox to try...

[RS Chris]

Top shaft is the same. The differential is different though. It will only fit B2, B3, T3 model trans case.

The final drive ratio is different also. 2:40 (b3) vs. 2:60 (b4).

[Mja75]

I thought the B4/T4 top shaft could fit to use the newer slippers in the B3, or is that just for the stealth gearbox? i too am planning on running a b3 in 40+ mod for fun, 10.5 to start ... i havent tried it yet to see. i have a plain T4 gearbox to try...

I've done the top shaft conversion on my B3 and T3, well worth doing. You can also then use a B4 gear cover, easier to find and more robust than the B3 one. At the moment I'm running a 13.5 in my B3.

[RS Chris]

I thought the B4/T4 top shaft could fit to use the newer slippers in the B3, or is that just for the stealth gearbox? i too am planning on running a b3 in 40+ mod for fun, 10.5 to start ... i havent tried it yet to see. i have a plain T4 gearbox to try...

I've done the top shaft conversion on my B3 and T3, well worth doing. You can also then use a B4 gear cover, easier to find and more robust than the B3 one. At the moment I'm running a 13.5 in my B3.

Is that a direct fit? Need one for my T3.

[Mja75]

Layshaft fits straight in, just don't put the spacer on like when it's fitted to a B4.
The gear cover won't fit over the T3 clutch though, but will of course fit if you use the B4 clutch.