Will I am not sure by what you mean a little more thickness? Is this the cross sectional area you are talking about? If so, the joint is still going to leak.
Why? The O-ring joint is designed for a certain size cross sectional area of an O-ring plus the inside and outside diameters. When I was designing hydraulic systems each port size was standard for a given O-ring size. What I would change was the material of the O-ring substituting Neoprene instead of BUNA-N or a different material depending on the nature of the median IE diesel-Gas or Hydraulic fluid.
Since your unit is a 2004 and it is now 2020, that is a pretty good life period for an O-ring in use. I was simple replace the existing O-ring with the same style and material. Why look for another issue by using an incorrect O-ring?
Just my $0.02
BTW I only did this for 40 years on and off at CAT.
2016 34RL CC; 2008 Ram Mega Cab 2500HD, 6.7L, 68RFE 6 speed, 4X4, Smarty S67, TDR 135K+miles