[dsraven]

in a shop I worked at long time ago we had a new fleet of diesel delivery vans to outfit, like the UPS style of delivery vans. the diesel engines were so loud the drivers complained constantly and the company asked us to spend some time (and money) on sound deadening. we ended up doing rubber curtains on each side of the engine, hung on rods that removed for easy access to the engine like an inner fender sort of, and used some hot water tank insulation on the firewall and hood. it is a foil backed (or fronted) material that seemed to work pretty well. a lot like the firewall insulation found on newer vehicles. some thick felt underlay under the carpet also works well. one old ford truck I rebuilt for a guy we sprayed the inner part of the cab with box liner, the kind that is sprayed commercially. we asked the sprayer to do several coats on the floor and under the dash so it would have a smoother floor because the truck was intended to be used for muddy off roading as well as daily driving and the guy wanted to hose out the interior. that was a really quiet truck inside and I have to think it was due to the thick layer of box liner inside the truck. the smooth floor was really quite nice too without any carpet. he thrwe down a carpet floor mat under his feet and it stayed put pretty well and was easily taken out if going into the bog.
just some ideas, sorry for the short novel. haha