Either it has one or it doesn't. If it came from Dr Diff. Contact him and he'll tell you. If it doesn't, you need one someplace in the line. if it doesn't, the first pump will be to refill the rear wheel cylinders. So yes its a possibility. You can also make a little dipstick and check the fluid level of the front reserviour - unless its the type which allows some sharing. Level will come up as fluid gets forced back.
Chrysler's tech tip was to gravity bleed the disks, and/or the old fashioned method or pump and close.
