Boeing C-135FR Stratotanker —

I think that should be KC-135

It's a T model that was designed to refuel the SR-71. It has a separate and isolated fuel system as the fuel (which is a gel)for the spy plane is not compatible with the fuel for the tanker. The R models can resupply themselves from their offload tanks as they have a separate valve (which the T models don't have) to facilitate this.

Jourdan would know the difference since he is an A&P and works on the KCs based in SLC. (Soon to be Pilot of a KC) Good luck Jourdan!