Small update here. I have a few things left to do before lifting the body off again and stripping the truck ready to paint the chassis, cab and sideshirts... (which I guess I've been putting off, as suddenly I won't have something that resembles an Overlander...) Seems to be a backwards step pulling it all off again, but I know it's not. Anyway, one of the jobs that needed finishing was the exhaust... connecting the manifolds to the modified Actros muffler I fitted 6 odd months ago... A day and some intricate pipework later and I had something that should work!! There's a few angles in the system that are not ideal, but if you had seen the size of the outlet pipes on the turbo engine manifolds (45 mm per side!!??) then this will be fine!
Here's the 3" pipework welded up, painted and in place. I have a deflector welded into the 'Y' piece, so both banks have the same area to breath into. Once I'd bled the fuel system (as it's not run for 6 months... Found the problem.. Lift pump hand pump plunger is knackered), the V6 burbled into life with a quiet deep note out of the muffler. I'd not heard this truck running with anything other than the rotten twin muffler system, but it's totally different now. Great result!