[68Gold/white]

I used to have a connection with a diesel shop, for the small (one ton) vehicles we worked on at my work's shop.
He recommended to replace a gear drive starter with the older direct drive starter because the direct drive starters actually spin the engine faster gear drive type. We performed such a swap many times, and it did help...

Let me know if you have any trouble getting the block heater cords. I may have some spares. I'd have to see the ends of your old ones to know for sure.

Tail pipes couldn't hurt the exhaust tone...

At my previous job (school bus dealer). We had a customer complaining about engine noise. The bus was a front engine transit type bus, the engine bay is next to the driver, has a dog house you lift up to get to engine. Very difficult to work on...........
My boss googles around and found a company that made insulating materials (I do not remember brand...). We bought a small roll of one inch theick flexible dense foam with a thick foil backing that also reflected heat. We put it on the back side of the engine cover, and a couple of other small areas. It made a HUGE difference in the noise level. I think you could accomplish the same with your diesel...some how...wouldn't take a lot of $$$ or time...mostly thinging of where to install. I'd at least cover the underside of the hood...