I'm currently putting an L20 engine in my 1200 ute... its fun. I'm not sure about the differences between the L18 and the L20, but i think they're very similar. I bought this engine and 5 speed box off someone who already had it in a 1200 ute, so all the mods had been made. came with extractors. I still had to make a few changes though
Mods i've made:
-reshape the sump (this was done for me, but it didn't look to hard, and i'd rather do this than modify the engine cross member)
-convert clutch from cable to hydrolic. haven't done this yet, but i'll get there
-oil pump clearance is tight near the sway bar. I've moved my motor back into the firewall a bit so that the oil pump sits behind the sway bar, but i think my car has been crashed (before i got it) the other guy had the oil pump above the sway bar, and he had the motor sitting heaps lower than i do, and had ground a bit out of one of the bolts for clearance.
-the tunnel in my car was too small to fit the 5 speed box with the motor back that far. If you keep it further forward, it should be alright, maybe a bit of massaging with a hammer... i ended up cutting the tunnel out of the 200b, now that was a nightmare, but my original tunnel was full of holes anyway
-remove the fan, and place an electric one in front of the radiator, behind the grill (I scored the radiator and fan aswell) i doubt the 180b radiator will fit, the 200b one definately wouldn't
-gearbox and engine mounts.... (obviously)
hope it doesn't sound too bad, i've heard someone say that the 180b motor fits straight in... I'm probably doing it the hard way
i've got a 120y diff in mine... a real weak spot. i'm expecting this to go first
sing out if you need more info