[neto]

I have a 3500 express with the same engines that came on the 4000 express (Cummins 6CTA)..... To replace the components between engine and fuel tanks has been a bit challenging, I have done pretty much everything from the alternator & starter (port) and aftercooler & waterpump (starboard) and this was without lifting the hatch.. You have to put your belly on top of the engine pretty much and make sure you have something to drink.. I would expect the 4000 to have a little more room to play and I bet the CAT 3208 take more space since its not 6 in line.