I'm new at this, so please be have patience. I have a 1996 3500.
I bought it new and like everything about it except the diesel noise it makes inside the cab. I seldom drive it because of the racket. There seems to be an area next to the back window where it is worse. I have a topper that may aggrevate the problem. What can I do to quieten it without spending a fortune?
Any help would be appreciated.

 

Welcome to the DTR family & Happy New Year.

Many have had success using a product called Dynomat to cover all metal surfaces under the carpeting (especially the are behind the rear seat. )
Here's a link to a thread about that subject.

https://www.dieseltruckresource.com/...hlight=Dynomat

Ed

 

Hello and welcome aboard there is alot of patience here,this is the place that has alot of great guys to help you,There are products out there to help like shovelhead stated, I have had good luck with wrapping the exhaust from the trubo to back behind the cab with moroso header wrap, also alot of noise and I mean alot comes from the oil pan, and the valve covers,there are products out there to sound deaden them, I have also had good luck on wrapping them with fire/high heat rated cloth, you can make it quieter it just takes some work. Goodluck, Rick