The oil pressure gauge on my 2004.5 2500HD Chevy Duramax with 4,600 miles reads a pressure of approx. 90 while I am accelerating and drops to approx. 32 while decelerating. While driving steady at most any speed the gauge reads 60.
I bought the truck new in Sept. of 2004. The only mods are an Astro Start remote starter, Trans Flo 45 Gal Fuel tank and 5th wheel hitch w/ Prodigy brake control.
This oil pressure fluctuation is something I just noticed yesterday. I do not believe that it has been happening for very long or I would have noticed it.
Any idea's would be appreciated. Thank you for any help.

Sounds completely normal.