I'm in the process of building up an 85 model
with CA18DET but haven't spoken to an Engineer yet. A friend got his SR20DET 1980 model engineered a few years back. I think a place in Carrum Downs approved it. What hassles are you having as I may face the same ones.

P.S. What suburb are you in?

Spud, Give Rama a call at Arrow Diffs in Sydney on 02-9526-5955. He made me up a very nice stainless steel 3 inch dump pipe to suit my 1200 - CA18DET conversion and it clears the idler arm and firewall nicely. I bought it a year or so ago but it was around the $220 mark I think. My was one of the first he did but he's got the template now. It will save you a lot of stuffing around!

I'm in the process of installing a R31 Skyline tank in my ute and reckon it's a good option as it has an inbuilt fuel pump and therefore does away with the extra expense of a surge tank and lift pump. I've also been told that the authorities prefer this option. The tank mounts where the spare wheel normally sits.
It's just a matter of welding in two 50x25mm
pieces of RHS steel between onto the chasis rails between the shocker towers and rear of the tray and then bolting the tank up to them. You can even still use the original fuel filling point by making up an appropriate connection to the new tank. I've removed the original tank and plan to mount my battery there.