All due respect to the OP but I think that the most likely scenario is that you are (were) mistaken about the truck asking for rear differential fluid change at the 37K interval. Keep in mind that the transmission fluid service also requires the changing of the front transfer assembly fluid at the same time. My guess is that either you are remembering that or that the service people actually mistakenly changed the rear diff instead of or in addition to the front transfer.
You are currently at the mileage that one would expect to be doing their second VT4 fluid service. In my experience, the maintenance minder system doesn't seem to vary much (in terms of mileage) when it come to the VTM4, transmission / transfer, and timing belt services. These services pretty much seem to coincide with the closest oil change to their "preferred" interval (VTM 15k, 45k, 75K etc , timing belt @105K). The oil change frequency does seem to vary with the type of driving.
It might be best to do your VTM4 service just to get back on proper schedule. . .
You are currently at the mileage that one would expect to be doing their second VT4 fluid service. In my experience, the maintenance minder system doesn't seem to vary much (in terms of mileage) when it come to the VTM4, transmission / transfer, and timing belt services. These services pretty much seem to coincide with the closest oil change to their "preferred" interval (VTM 15k, 45k, 75K etc , timing belt @105K). The oil change frequency does seem to vary with the type of driving.
It might be best to do your VTM4 service just to get back on proper schedule. . .
