Is the transmission non-serviceable? I was thinking of adding a cooler, but when I looked for a dipstick there was none. I read in the manual that the tranny shouldn't need service for 150K. I understand the deal with FMC not wanting to cover mess-ups on fluid selection, but what if you wanted to add a cooler or flush you own? I've done the R-4100 many times on the 7.3's and is really easy.............only takes 5 4 gallon jugs. Can we not check or add fluid to this tranny?