V8 and 6Cyl gearboxes

**Dick61** · 14-04-2014, 04:59 PM

Just wondering, is there a difference between a 6 or a v8 tailshaft, I know tonners run larger unis but if you change from a 6 to a v8 with associated box, do you have to change the tailshaft?

**HK1837** · 14-04-2014, 08:19 PM

Apart from cab-chassis yes. 6cyl run smaller uni front and rear and thus the yoke at the gearbox and the yoke at the diff are smaller. You can fit say a 253 and trimatic where a 173 and trimatic were and use the same tailshaft but legally you cannot use it on the road as the universal joints are not rated for the engine.

Cab chassis all used the same front and rear uni regardless of engine or gearbox.

Basically goes like this for sedan and coupe (ignoring optional HD rear axle on 6cyl):

Tailshaft 1 - 6cyl HQ-HZ sedan and coupe. Small unis on both ends.
Tailshaft 2 - 253 HQ-HZ sedan and coupe, 308 HQ sedan and coupe, 308 manual HJ-HZ sedan and coupe, 308 TH350 HZ sedan. 1" cup V8 unis on both ends.
Tailshaft 3 - 308 TH400 HJ-HZ sedan and coupe. 1.125" cup uni on gearbox end, 1" on other end.
Tailshaft 4 - 350 HQ sedan and coupe. 1.125" cup unis on both ends.

Works the same for HQ-WB wagon, ute, van and Statesman (these are all the same length for the same engine and box).

Cab chassis only have 2 x shafts, both are 1.125" cup unis on both ends:

All except 308 TH400 HJ-HZ.
HJ-HZ TH400 (same as above just shorter).

**thatotherguy** · 15-04-2014, 05:13 PM

I have a diff from a HQ 350 statesman,if i want to put it in my sons HQ prem with a 253 do i need a different tailshaft or just different uni?

**Cocko750** · 15-04-2014, 06:56 PM

Originally Posted by thatotherguy

I have a diff from a HQ 350 statesman,if i want to put it in my sons HQ prem with a 253 do i need a different tailshaft or just different uni?

You could swap yokes between your diffs ,or get a new uni with v8 size one side and 350/tonner the other,I'm sure you could do either the diff is the same just yokes are bigger on 350/tonner as was said earlier