When the diesel motor in my 1991 Hilux 4x4 decided that it didn't want the 4th piston anymore and threw it on the M5 one Sunday morning .. I decided right then and there to NEVER have a 4 cylinder diesel again !!!!!
So I went for the Ecotec V6 .. now don't get me wrong I HATE Holdens but the marry up was perfect .. The extra power was brilliant for everything from being able to beat the ***** in the right lane at a set of Traffic lights to going bush and climbing all over rocks.
But there is a down fall and it's all in the gear box .. Marks adapters does have the conversion plate for V6 motor to hilux box (I actually got mine from Dello's in Sydney because 1 I lived in Sydney and 2 they were cheaper ) .. But the Luxy box just can't handle it .. I went through 4 boxes in 2 years .. You can go a Dyno truck box (Again Marks adapters has the conversion kit) but the box alone was around $2k - $2 1/2K then the conversion kit on top of that .. But honestly it's the only way to go if you're looking at the Ecotec V6.
Have fun which ever way you go ^_^