I am in the process of replacing the rear housing of a NP 246 transfer case. This unit had the notorious oil pump rub issue. I followed directions from the manufacturer of a new oil pump for reassembly of the case halves. The online tutorial tells me to be sure that the shift shaft spring is in place before assembly of the case halves. I have been very careful on this project, but it seems that I do not have the said spring. Could they be speaking of another model, or have I misplaced the spring? Thanks in advance.